ISSN: 2157-7617

Journal of Earth Science & Climatic Change
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  • Brief Report   
  • J Earth Sci Clim Change, Vol 13(6): 623
  • DOI: 10.4172/2157-7617.1000623

1981-2021 Earth Climate Warming: Contribution of CO2 and Milankovitch Cycle

Felix Kogan*
National Oceanic and Atmospheric Administration (NOAA) 1315 E West Hwy M2, Silver Spring MD, 20910, USA
*Corresponding Author: Felix Kogan, National Oceanic and Atmospheric Administration (NOAA) 1315 E West Hwy M2, Silver Spring MD, 20910, USA, Tel: +3017700995, Email: felix.kogan@noaa.gov

Received: 02-Jun-2022 / Editor assigned: 06-Jun-2022 / PreQC No. jescc-22-65912 (PQ) / Reviewed: 20-Jun-2022 / QC No. jescc-22-65912 / Revised: 23-Jun-2022 / Manuscript No. jescc-22-65912 (R) / Accepted Date: 23-Jun-2022 / Published Date: 30-Jun-2022 DOI: 10.4172/2157-7617.1000623

Abstract

In the recent two centuries, the Earth’s climate has been warming. By 2020, the Earth’s mean temperature anomaly ((TA), relative to the 1850-1900 mean Earth temperature) increased by nearly 1.1oC, leading to never before experienced environmental, economic and social events. The warm climate has triggered many extreme droughts, followed by hunger in Africa, withering heat in South Asia, multi-year forest fires in North America, devastating hurricanes in Central America and other unusual events. World scientists and society are indicating that the main cause of the Earth’s climate warming is an increase in anthropogenic greenhouse gases, specifically human-produced CO2, which intercepts infrared (IR) solar radiation from the Earth’s surface and re-emits the IR back, warming land surface and air. Meanwhile, climate modeling has recently showed that CO2 contribution to Earth’s climate warming is much less than 30%. Assuming that CO2 contributes 25% to global TA increase and considering that by 2020, the Earth’ climate temperature anomaly increased by nearly 1.1oC, this paper is estimating that CO2 has increased global temperature by 2020 to 0.28oC. Further, this investigation has shown that the rest 0.82oC (from 1.1oC) climate warming has been contributed by the interglacial climate period from the multi-year Milankovitch precession cycle.

Keywords

Earth temperature; Carbone dioxide; Climate warming; Ozone depletion; Milankovitch precession cycle

Introduction

Since the mid-18th century, the Earth’s climate has been warming [1]. From the early 1980s, this process has intensified and, by 2020, the global mean temperature anomaly ((TA), relative to 1850-1900 mean T) increased by nearly 1.1oC (NOAA/NCEI 2021, IPCC 2021, Vigileone 2021). Strong global TA increase between 1981-2020, led to unusual environmental, economic and social events (UNESCO 2018, NASA 2018, 2017, NOAA 2017, 2016, NOAA/NCEI 2017, IPCC 2021, 2020, 1919 a-f, 2014, 2007). Some countries during that period suffered from anomalous heat, shortages of rains and harsh and snowy (or opposite) winters, atypical for those places. Warm climate triggered many extreme droughts, followed by hunger in Africa, withering heat in South Asia, multi-year forest fires in North America, besides droughts, there were also devastating hurricanes in Central America, intensive high coast US land floods in 2017 (IPCC 2018, NOAA/ Climate.gov 2018) and other disasters.

Climate experts and media are warning that climate will continue to warm in the future, resulting in the further reduction of ice area, especially in the Northern Hemisphere, ocean level increase and the intensification of natural disasters leading to unusual agricultural and socio-economic consequences. Among them, a reduction of crop production and deterioration of food security will lead to a considerable increase in the number of hungry people in the developing countries (FAO 2018, 2017, IPCC 2007, 2014, 2019 a, b). There are indications that following global warming, between 1981-2020, countries of Africa, Southeast Asia and South & Central America suffered from a lack of food and population hunger in the years of disasters, especially droughts [2].

Currently, world scientists and society are pointing out that the main cause of the Earth’s climate warming is an increase in anthropogenic greenhouse gases (GHG) emission (carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O)). From all of them, human-produced CO2 is firmly considered as the main stimulator of global warming (IPCC 2021, 2019 a-f, 2014, 2007, WMO 2018). There are indications that CO2 has increased in the atmosphere since the pre-industrial era, contributing to climate warming and also ocean acidification (IPCC 2007, 2014, 2019). CO2 in the atmosphere intercepts infrared (IR) solar radiation from the Earth’s surface and re-emits the IR back in all directions warming land surface and air (Fecht 2021). Therefore, in the past 20-30 years, there has been a strong focus on the need to reduce CO2 emission in order to slow down climate warming (IPCC 2007, 2014, WMO 2015, WEF 2016, UNEP 2016, UNESCO 2018).

Meanwhile, scientists, studying climate, have indicated that the global climate is controlled by many external and internal factors [3]. The external factors include the Sun, the Sun-Moon gravitation, the Earth inclination towards the Sun and other parameters. The internal factors include atmospheric temperature and pressure, oceanatmosphere thermal balance, large-scale atmospheric circulation pattern (for example, North Atlantic Oscillation) etc. If the Earth’s climate is regulated by so many parameters, how can only one environmental factor, CO2, which has never caused global warming in the past million years (Ward 2016), presently control climate warming? Limited data has been used in to prove the CO2 increases the Earth’s temperature (IPCC 2014, Gore 2006). Therefore, this paper attempts to double investigate the relationship between CO2 and global TA (IPCC2014, Gore 2006). This paper has also investigated other environmental factors contributing to global Earth warming.

Global Climate Warming and Major Earth Changes

Global temperature measurements showed that in the past 170 years, the Earth’s climate has been warming, especially between 1981- 2020 (IPCC 2021, 2007). The average global temperature anomaly ((TA), relative to pre-industrial time global mean temperature) during the indicated strongest climate warming increased by nearly 1.1oC by 2020. The past 40 years (1981-2020) have been extremely hot, stimulating the development of some very unusual global environmental events (IPCC 2021, 2020). Climate warming has induced ice melting in the North Pole; the area was reduced by nearly 2 mil, km2 (from 11.5 to 9.5 mil. km2 (Figure 1b and d) from 1980s to the 2010s (IPCC 2014, 2012)). As the result of an intensive ice melting, the sea level has been rising a few cm from the mid-1980s (Figure 1c) and it is expected, that by the end of the current century, the world’s ocean will be at least two feet higher (IPCC 2014, 2007).

Long-term global temperature data shows world climate warming impacts on land. For example, many primary agricultural lands are experiencing hot weather and shortages of rainfall during the growing season. Following (Figure 1g), the amount of water from snow in the Northern Hemisphere has been reduced from the 1980s, when intensive global warming began. Figure 1e shows the reduction of such natural disaster as tornadoes between the 1950 and 2017. (Figure 1f) displays a strong increase in greenhouse gas (GHG) emission, especially CO2, which increased from 315 to 390 ppm between 1950-2010.

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earth-science-climatic-change-Summary

Figure 1: Summary of the major Earth changes due to global warming. (a) Mean land and ocean temperature anomaly (TA) during 1880-2020 (TA, relative to pre-industrial time mean temperature); (b) Sea ice area in the Northern Atmosphere (1970-2020); (c) Sea level during 1990-2015; (d) Arctic sea ice extend by 10-year periods (between 1980s and 2010s); (e) Number of tornadoes during 1950-2017; (f) Globally average greenhouse gas (GHG) concentration during 1850-2012; (g) Snow area in Northern Hemisphere (1920-2012); (h) Ocean temperature during 1960-2016 (IPCC 2019a-f, 2018, 2014, WMO 2017, 2014, NOAA 2017. UNESCO 2018, NASA 2018, 2017, NOAA 2017, 2016, NOAA/NCEI 2017, Eilpering et al. 2019, Dennis & Mooney 2018, FAO 2018, 2017, Alexandratos and Bruinsma 2012)).

p>Following a world climate investigation, it was reported (IPCC 2014) that in the past 20-40 years, global warming has caused some changes in biological systems (plants, birds, insects etc.). For example, climate warming has induced an earlier spring beginning in the southern US, prompting insects to move to Texas (US) earlier than before and providing food for bats. Therefore, bats are migrating to Texas roughly two weeks earlier (mid-March instead of late March) than they had been in the prior 22 years [4]. Some world agricultural areas indicated a reduction of crop production. Meanwhile, the US Midwest is showing an increase in corn and soybean production due to wetter summers in the recent decade. A very important issue of climate warming consequences is drought intensification and expansion, water shortages and the gradual general deterioration of agricultural system, which is expected to affect 5 billion people by 2050 (UNESCO 2018, Watts 2018).

What is Controlling Global Warming?

Climate System

Principally, climate system regulates the Earth’s climate. This system is highly complex consisting of (1) Earth’s internal components, (2) Earth’s external components and (3) additional internal components (Table 1). The major internal components include the atmosphere, hydrosphere, cryosphere, lithosphere, biosphere and their interactions (Sciencing 2019, Springer Link 2016). Internal components (water, temperature, and biosphere) create basic life on Earth [11]. Additional internal contributions are the distribution of land and ocean, the geographic features on land, ocean bottom topography etc [5]. The atmosphere, the most unstable part of the internal system, contains many environmental parameters (cloud, aerosols, carbon dioxide (CO2) etc.), which might control short- and long-term performance of the climate system.

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Earth internal components Earth external component Additional Earth’s internal components
Atmosphere Sun & its output Distribution of land
Hydrosphere Earth's rotation Distribution of ocean
Cryosphere Sun-Earth geometry Geographic land features
Lithosphere Precession (changing orbit) Ocean bottom topography
Biosphere   Vegetation
Interaction between them Included Included

Table 1: Earth climate system.

p>External components of the Earth’s climate system include the Sun, the Sun-Earth geometry, the sun-moon gravitation toward the Earth’s precession and others. The Sun is the major component of the external system, keeping our planet warm and preventing it from being only as an ice-coated rock. Circulations in the atmosphere and oceans are primarily driven by solar radiation and transport heat from the tropical regions to regions that receive less energy from the Sun. The water cycle also moves energy throughout the climate system. The Earth’s

CO2 and Climate Warming: Current Understanding

Currently, the world’s governments, policy makers, UN organizations and many scientists are promoting carbon dioxide (CO2) increase as a stimulator of global warming (IPCC 2021, 2020, 2019ag, 2018, 2014, 2007, Fetch 2021, NOAA/NCEI 2021, NASA 2021, UN 2016, UNFCCC 2015, 2014). CO2 is released into the atmosphere from fuel burning (wood, oil, natural gas, diesel etc.) cement production, deforestation increase and other human activities. CO2 in the Earth’s atmosphere acts as a blanket, trapping IR radiation, emitted from the Earth [7]. Following this opinion, CO2 is a single environmental parameter in the atmosphere, causing the current climate warming. Therefore, the UN-based Kyoto Protocol and the subsequent Adaptation Fund were the first steps to encourage the international community to begin working on the goals of CO2 reduction (UNFCC 2014).

A very intensive global campaign for CO2 reduction has begun from the publication of the Book “Inconvenient Truth” (Gore 2006) and issuing a film with the same title. These sources have been focused mainly on the diagram, showing an intensive increase in CO2 time series and the matching increase in general trend of global temperature anomaly. So, the matching CO2 and TA trends have been presented as proof that a strong increase in CO2, stimulates global temperature increase (Gore 2006). The IPCC Report (2014) has confirmed Gore’s idea using larger data sets showing that global warming is stimulated by an intensive CO2 increase. Some of Gore’s (2006) climate warnings statements have been quite scary: “the world at the edge of climatic catastrophe if not stopped emitting CO2, we come to the point of no return.” The IPCC (2014) has added: “CO2 is the largest single contributor to radiative forcing over 1750-2011 and its intensive upward trend since 1970”, “causing pervasive and irreversible impacts for people and ecosystem”.

Meanwhile, we should emphasize again, that the Earth’s climate system is extremely complex and is controlled by many parameters (the sun, ocean-atmosphere thermal balance, large-scale atmospheric circulation pattern, and land surface structure, ice in the Northern and Southern Poles and many others). Having so many parameters impacting climate, how can only one environmental parameter, CO2, which has never caused global warming in the past million years (Ward 2016), presently control climate warming? Moreover, how can CO2 trap so much heat if it makes up only 0.04% of the atmosphere composition (Scep Sci 2019, Codington et al 2016)? In 1900, K. Angstrom, a well-known physicist, showed in lab experiments that CO2 warming effect is very minimal (Ward 2016). Currently, some climate modelers indicate overestimation of CO2 impacts on Earth’s temperature increase [8]. A very interesting CO2 investigation has been performed by Rougemont (2015). After modeling the impacts of six environmental parameters’ (including CO2) on climate, Rougemont came to the conclusion that CO2 contribution to global temperature increase is much less than 30%. Let’s assume that CO2 contributes 25% to global TA increase. Considering this assessment and that during 1980-2020 global temperature anomaly increased by nearly 1.1oC (NOAA/NCEI 2021, NASA 2021), calculations indicated that CO2 has increased global temperature by 2020 nearly 0.28oC. Following this TA increase from CO2, what climate parameters contributed to the rest of the rest of 0.73oC global TA warming during 1981-2020?.

Matching CO2 Dynamics and TA Trend: New Analysis

Following the above discussion, we can identify two opposite issues. First, the world is firmly accepting the idea that CO2 is warming the Earth because (a) CO2 is absorbing the IR radiation from the Earth surface (IPCC 2021, 2019a-f, 2014, 2007, WMO 2018) and (b) a very close matching CO2 and TA upward long-term trends is a major proof that the growing CO2 is increasing global TA (Gore 2006, IPCC 2014). Second, there have been many concerns against the idea that CO2, a single environmental parameter, is warming the world [9]. Therefore, we are analyzing again 162-year CO2 and TA time series (IPCC 2014), which long-term matching trends have been accepted as a major proof that CO2 is a single environmental parameter, increasing global TA (IPCC 2014, Gore 2006).

We have started analysis from Figure 2, displaying 162-year (1850- 2012) time series of global CO2 and TA. During the investigated period, global Earth mean TA has increased from -0.7 in 1850 to +0.3°C in 2012 and CO2 has increased from 281 to 398 ppm (IPCC 2014). Following a very general long-term (162-year) dynamics of the two parameters, their general trends have matched (IPCC 2014) and this match has been accepted as a general rule, that CO2 is causing global warming (Gore 2006, IPCC 2019a-f, 2014, Fetch 2021, Codington et al 2016, UN 2016, UNEP 2016, UNFCCC 2015, UNFCC 2014, NOAA/NCEI 2007).

Meanwhile, investigating annual dynamics of CO2 and TA in Figure 2, it is noticeable: first, annual CO2 is increasing very smoothly, while annual TA is jumping (up-down). Therefore, TA required trend derivation (red curve). Second, comparing general 162-year estimated TA trend and CO2 time series, we should confirm their close visual match, especially after the 1980s, when both parameters increased more intensively. As the IPCC (2014) indicated “ the period from 1983 to 2012 was likely the warmest 30-year period of the last 1,400 years in the Northern Hemisphere,” when “the global average combined land and ocean temperature data calculated as linear trend, show a warming around 0.87°C”.

Investigating further, the time series in Figure 2, our next question was: if the general rule is applied to the entire 162-year match of CO2 and TA time series, can we apply that general rule to shorter periods from the same 162 years (IPCC 2014). A very careful examination of the 162-year TA time series, indicated availability of 15-34 years TA periods with a certain type of trends. Among these periods we found two, which attracted our attention. During 1874-1908 (34-year) and 1971-1996 (25-year), CO2 increased by 9 and 16 ppm, supposedly stimulating TA growth. Meanwhile, the TA during these periods had cooling trends, decreasing from -0.5 to -0.72 and from -0.32 to -0.43, correspondingly.

The presented two cases (34 and 25 years) of mismatch between

earth-science-climatic-change-time

Figure 2: The 162-year (1850-2012) time series of (a) global mean TA (relative to the 1986-2005 mean temperature) and (b) Mauna Loa’s CO2 measurements (IPCC 2014).

CO2 and TA time series are indicating that the general rule (matching CO2 and TA trends are proving strong CO2 impact on global warming) is not working in these two 34-year and 25-year periods. Following the two cases of CO2 and TA mismatch, we investigated all cases of short-term (15-34 years) TA and CO2 trends during the 162-year. (Figure 3(a)) displays these short-term TA trends, shown by red lines.

For each of the periods, with a certain trend, we derived the TA trend change (increasing, decreasing, and stable) and the corresponding CO2 increase values (Figure 3(b)). Since the 162-year time series (IPCC 2014) ended in 2012, the last 8-year (2013-2020) of TA and CO2 time series were investigated from Figure 3(c) (NOAA/NCIE 2021, NASA 2021).

The summary of Figure 3 is presented in Table 2. This table contains the TA differences for each trend line (red), derived as TA at the trend’s

earth-science-climatic-change-series

Figure 3: The 162-year time series (a) global mean TA and (b) atmospheric CO2 (IPCC 2014), separated by vertical lines by the 15-34 years periods with the estimated TA trends (red lines). Between the (a) and (b) diagrams are shown: the years of the trend beginning and end, TA (deg C), estimated from red lines, CO2 (ppm), estimated at the intersection of vertical lines with CO2 time series; (c) the 1880-2020 TA and CO2 (NOAA/NCRI 2021, NASA 2021).

end minus TA at the trend’s beginning. A positive TA difference number indicates a warming TA trend, a negative TA difference number indicates a cooling TA trend and a zero TA difference number indicates a stable trend (no increase and no decrease). The second line of the Table 2 is CO2 differences for the periods of TA short-term trends (red line n TA trend and vertical lines for both diagrams). The CO2 numbers are derived from CO2 time series curve intersected by vertical line in Figure3. Similar to TA, CO2 difference is calculated as CO2 values for the same years the TA difference is calculated. The CO2 differences in Table 2 are always positive, following a stable increase of CO2 time series in Figure2, while TA is changing.

Following global TA in Figure 3, we derived seven 15-34 years (except the last one, which provides preliminary estimate) periods from a 170-year time series (IPCC 2014, NOAA/NCIE 2021, NASA 2021). Table 2 is estimating short-term (years are indicated in the head of the table) global TA trend differences (end minus beginning) and the corresponding CO2 trend differences (similar to TA). Previously, we have discussed two periods of CO2 and TA mismatch, indicating that when CO2 is increasing, global TA is decreasing (cooling). In Table 2 these two periods (1875-1908 and 1939-1975) are showing that CO2 has a positive trend, while global TA has a negative trend. From the rest of the Table 2 columns, in two of them (1908-1939 and 1975-1998) CO2 b> and TA are matching, both having positive signs. Meanwhile, Dr. Ward’s (2016) investigation has shown that global TA increase during 1975-1998 was caused not by CO2 increase, but by a strong ozone (O3) reduction (from chlorine) following a penetration of solar radiation to the Earth surface and warming it. In the remaining three columns (1850-1875, 1998-2012 and 2013-2020), CO2 has positive signs (increasing trends), while the TA has a zero number, indicating flat trends (no increase and no decrease). In these three cases, flat TA trends are indicating that CO2 is not causing global warming or an increase in TA during that period.

 

Parameter 1850 – 1875 1875 -1908 1908 -1939 1939-1975 1975 -1998 1998-2012 2013-2020
TA   0 -0.13 +0.40 -0.11 +0.68   0     0
CO2 +3 +9 +15 +18 +27 +20 +14

Table 2: Difference in the trend values between the end of the year (the second number) and the beginning of the year (the first number). If TA numbers have minus sign and zero value and CO2 number has positive sign, this indicates that CO2 has not caused global warming during the indicated period.

Summarizing Table 2 and Figure 3 results and their analysis from eight cases of the identified short-term TA trends, it was found that in six of them increasing CO2 (positive sight) has not matched with global TA increase (warming). Following all these results, we came to the conclusion that the growing CO2 in the atmosphere can increase TA (intercepting IR from the Earth). Meanwhile, the CO2-based TA increase in the atmosphere is estimated much less than 30% [10]. The second component, CO and TA match, presented by Gore (2006) and IPCC (2014) as proof that CO2 is warming the world has not received confirmation in the above investigation (Figure 3 and Table 2).

New Ideas about the Causes of Global Warming

In the recent several decades, there have been many different ideas about global warming in addition to the widely accepted statement that only CO2 is triggering global TA increase. They included changes in solar activity, changes in large-scale atmospheric circulation patterns (ENSO, NAO, AO etc.) and many others [11]. One of the new ideas came from the Book by Dr. Peter. Ward (“What Really Causes Global Warming?” 2016). This Book has not only discussed the new causes of global warming, but also has investigated deeply physical principles of greenhouse gases, their impacts on global TA increase-and other related topics.

Ozone Depletion and Global Warming

Ozone (O3) is a colorless gas in the stratosphere. It absorbs very energetic ultraviolet type B (UV-B) Sun’s radiation, protecting living things on Earth. Absorbing UV-B radiation, the ozone is also preventing the Earth from warming. Unfortunately, the process of ozone depletion began in the 1960s following human activities in using widely chlorofluorocarbon gases (CFC) as refrigerants, paints, perfumes, lubricants, cooking oil and others (Ward 2016, 2016a). By 1974, scientific research has shown that when CFC gases have risen to the lower stratosphere, they have been broken down by UV-B radiation, resulting in a release of chlorine, which had destroyed ozone. It was estimated that one chlorine atom might destroy up to 100,000 molecules of ozone through a catalytic reaction (Ward 2016, 2016a).

The process of ozone destruction was very extreme in Polar Regions, resulting in the development of the ozone hole over Antarctic in 1985, where ozone was depleted in half. It was slightly less depleted in the Arctic, up to 15% in mid-latitudes and very little in the tropics [12]. Following the chlorine-based destruction of the ozone shield, the Earth began to warm up [9]. It was clear that global society must stop releasing CFC gases into the atmosphere. Following this goal, the United Nations’ Montreal Protocol limited manufacturing of CFC gases. As the result, by 1993, chlorine increase in the atmosphere stopped, by 1995, ozone depletion stopped and by 1998, the global temperature increase stopped as well.

Following these events and research [13], a diagram was developed. Figure 4 shows 1945-2014 dynamics in global TA and CO2 in the atmosphere, O3 and chlorine (CH) accumulation in the stratosphere. Analysis of diagram shows that O3 depletion has initiated as soon as CH began to increase in the early 1970’s. Following CH-based O3 reduction, global TA began to increase strongly (from +0.12 to +0.61 C) between 1973 and 1993. In 1993, when CH in the atmosphere has stopped increasing, leaving O3 at the highest level (315 Dobson units), TA stopped increasing and have a stable flat trend at 0.61o C during 1993-2014. Thus, CH-related O3 has regulated TA changes: increase during 1970’s-1992 and stability during 1993-2914.

Earth Climate and Milankovitch Cycle

The Sun supplies the Earth with energy, bringing life to the planet. The Earth climate is controlled by many factors. First of all, it is the Sun and many annual environmental parameters [14]. Secondly, the

earth-science-climatic-change-temperature

Figure 4: 1945-2014 global mean temperature anomaly (TA, Degree C), carbon dioxide (CO2, in Parts per million), ozone (O3, in Dobson units) and chlorine in (Part per billion) from CFC gases (Kogan 2018, Ward 2016).

Earth’s climate is also controlled by multi-year cyclical movement of Earth relative to the Sun at different time scales, from years to decades, centuries and millennia. Therefore, the Earth’s climate changes are controlled by the first: annual environmental parameters and the second: multi-year Earth cyclical position relative to the Sun. The second component provides extreme variations in Earth’s climate. The mechanism of the Earth’s multi-year cycle and climate variations was introduced by Milankovitch one century ago [15].

One of the important components of the Milankovitch cycles is collective effects of changes in Earth movement around the Sun on its climate over thousands of years. Milankovitch hypothesized that such Earth cycles (relative to the Sun) as eccentricity, axial tilt, and precession (Figure 5a) resulted in cyclical variation of solar radiation reaching the Earth and regulating multi-year Earth climatic patterns (Hoken 2021, Askinglot 2019, Muller 2015, Dehan & Mathews 2015, Marshall 2010, Prigs 2010). Milankovitch studied the Earth’s orbital variations for the last 600,000 years and calculated the amount of solar radiation, reaching the Earth due to changes in the Earth’s orbital parameters (Buis 2020, Tierney et al 2020).

The eccentricity regulates the shape of the Earth’s orbit around the Sun. This orbit is close to circular, but due to the influence of the big planets (Jupiter, Saturn), the orbit might change to slightly elliptical with 100,000 years cycle. The axial tilt (known as obliquity) is the angle of Earth axis, tilted to the Earth orbital plane. The angle is changing between 22.1-24.5 degrees during a 41,000-year cycle. Following this

earth-science-climatic-change-Milankovitch

Figure 5: Milankovitch cycle with special emphasis on (a) eccentricity and tilt and also Earth precession ((a) and (b)).

cycle, the Earth’s seasons receive more radiation during the summer, when the Earth is tilted towards the Sun and much less radiation during the winter, being tilted out of the Sun. The precession cycle occurs due to the gravitational influences of the Sun and Moon that cause the Earth to bulge at the equator, affecting its rotation. The cycle of axial precession spans about 25,771.5 years. Figure 5a provides geometrical explanation of the Milankovitch cycles (Buis 2020).

Milankovitch’s Precession Cycle

From the three Milankovitch cycles, the precession is the shortest and the best to explain the long-term Earth position relative to the Sun and the corresponding potential of climate changes (Figure 5b). The precession-based Earth variation (or wobbling) relative to the Sun is very slow. It takes the Earth nearly 26,000 years to complete a single Earth’s axis precession circle and around 13,000 years for a half the circle. In the Earth’s slow wobbling, the extreme tilts of the axis stay roughly constant at + 23.5 and -23.5o from imaginary line. Tracing the Earth’s axis out into space, the extension of the axis for a complete precession circle tracing a conical shape (Figure 5b).

Following global TA

Precession-based Earth Climate

Regarding climate temperature, it is important to emphasize that the Milankovitch precession cycle does not estimate the Earth’s temperature. The cycle assesses only the general direction of the Earth’s axis tilt towards the Sun and following that, if the Earth receive more radiation (tilted closer to the Sun) or less radiation (tilted out of the Sun). The most recent ice age was nearly 13,000 years ago, when the Earth had been tilted in extreme position out of the Sun. Geological researches have indicated that there have been many ice ages long before humans made their appearance. Some ice ages were comparatively mild, but others were so severe that most of the Earth had been frozen over for tens or even hundred thousand years (Marshall 2010).

Following the Milankovitch precession cycle, the recent ice age (nearly 13,000 years ago) was associated with the Earth’s axis being far from the Sun (Figure 5b), resulting in the planet receiving much less solar radiation and having a correspondingly negative Earth temperature and the ice age period. Ice during the discussed ice age period covered the majority of North America (up to the central US), much of northern Europe and Siberia (slightly below their central latitudes (Pigs 2010)). Since ice covered huge areas, containing much of Earth water, the level of global ocean during that period has been 110- 200 m lower than now (Marshall 2010, Prigs 2010). The next ice age will be after the end of the current interglacial period (Tierney et al 2020).

Currently, the Milankovitch precession cycle indicates that Earth is in interglacial climate periods, which is a period of warm climate, between the neighboring multi-year ice ages. This warm climate has been followed by the recent 13,000 years ice age, when the Earth has gradually tilted towards the Sun. During the period of the Earth’s axis being closer to the Sun, global temperature was the highest. Figures 1a and 2a confirmed a strong increase in global mean temperature anomaly ((TA) relative to pre-industrial time mean temperature) during the late 1970’s - 2020. Therefore, not explained previously the 0.73oC (part of 1.1oC) TA increase during 1981-2020, has been associated with the interglacial Milankovitch procession cycle, when Earth has been tilted towards the Sun.

Currently, according to the Milankovitch precession cycle, the Earth is coming out of a warm period and should be experiencing a cooling trend transitioning gradually into another ice age. This was confirmed in the recent years by NASA satellites, which have detected a reduction in the amount of solar radiation reaching Earth, suggesting that we should be experiencing a gradual cooling (Buis 2020). This is also has been confirmed by TA during 2016-2020, when after 40-year of intensive global TA increase, during the most recent 5-year (2016- 2020), TA has stopped increasing (having a flat trend). Following the precession cycle, this is the transitioning to the new ice age in the next several thousand years.

Summary

In the recent two centuries, the Earth’s climate has been warming, especially between 1981-2020, when global mean TA increased by nearly 1.1oC. An intensive Earth warming has led to unusual environmental, economic and social events. Warm climate has intensified many extreme disasters, followed by hunger in Africa, withering heat in South Asia, multi-year forest fires in North America, devastating hurricanes in Central America and others.

World society has accepted that the main cause of Earth climate warming, are greenhouse gases (GHG), specifically human-produced CO2. One proof was the increasing match between multi-year CO2 and TA trend time series Therefore, in the past 40 years, there has been a strong focus on the need to reduce CO2 emission in order to slow down climate warming.

Meanwhile, scientists, studying climate, emphasize that the Earth climate is controlled by many factors (atmospheric temperature and pressure, ocean-atmosphere thermal balance, Earth inclination towards the Sun and many others). If Earth climate is regulated by many environmental factors, how only one of then, CO2, which makes up only 0.04% of the atmosphere composition, can control the entire Earth warming?

Since an increasing match between CO2 and TA long-term time series is the major poof that CO2 is warming Earth climate (Gore 2006), and the data, expanded to 162 years (IPCC 2014) confirmed that, we produced a new analysis CO2-TA relationship using the same data, which were used to persuade the world that CO2 is warming the Earth.

If CO2 correlates with TA trend for 162 years, they supposed to correlate for shorter periods as well. Therefore, we correlated CO2 with TA for the 15–31-year periods, total eight. Finally, from the eight periods of 15-31 years long, it was found that in seven of them, increasing CO2 has not matched with global TA increase (warming).

We should admit, CO2 in the atmosphere increase temperature, intercepting IR emitted by Earth and re-emitting IR back to Earth land and atmosphere. Meanwhile, based on modeling the impacts of 6 environmental parameters, including CO2, on climate warming, the CO2 contribution to climate-based TA increase in the atmosphere is estimated to be much less than 30% (Rougemont 2015).

Let’s assume that CO2 contributes 25% to global TA increase. Considering this assessment and that by-2020 global temperature anomaly has increased nearly 1.1oC (NOAA/NCEI 2021, NASA 2021), calculations indicated that CO2 increased global temperature by 2020 nearly 0.275oC. Following this TA increase from CO2, what climate parameters have increased the rest of 0.825o C global TA during 1981- 2020?

The 0.82oC climate warming is controlled by Milankovitch precession cycles (25,771 years), related to changes in Earth movement around the Sun, corresponding amount of energy received and climate change (ice age and warm) over thousands of years. Currently, following this cycle, Earth is in interglacial climate periods (warm climate, between the neighboring multi-year ice ages (13,000 years ago and the next one). Earth is currently gradually tilted toward the Sun.

References

  1. Abdullah S (2020) 3 Types of Earth Movements: Earth Rotation, Earth Revolution and Precession. Note Read.
  2. Google Scholar

  3. Australia Government (2017) Wheat. AG.
  4. Australia Government (2016) Australia’s Reference climate Station Network. AG.
  5. Askinglot (2019) What is the precision cycle?. AL.
  6. AWXB (2018) Australian wheat. AWB.
  7. Alexandratos N, Bruinsma J (1980) World Agriculture towards 2030/2050: The 2012 Revision. ESA Working 12-03.
  8. Indexed at, Google Scholar, Crossref

  9. Anlyzers (2019) Measuring atmospheric carbon dioxide. Control.
  10. Google Scholar

  11. Anderson BA, Silver BD (1990) Growth and diversity of the population of the Soviet Union. Ann Am Acad Political Soc Sci 510 (1); 155-177.
  12. Indexed at, Google Scholar, Crossref

  13. Ankit J (2015) Ozone layer depletion: Causes, effects and solutions. Continents 18.
  14. Google Scholar

  15. Alley RB, Andrews JT, Brigham-Grette J, Clarke GKC, et al. (2010) History of the Greenland Ice Sheet: Paleoclimatic insights. Quat Sci Rev 29(15):16; 1728-1756.
  16. Indexed at, Google Scholar, Crossref

  17. Baede APM, Ahlonsou E, Ding Y, Schimel D, et al. (2018) The Climate System: an Overview. IPCC 87-98.
  18. Indexed at, Google Scholar

  19. Bastasch M (2017) China is “Sticking to the Paris Agreement in Name Only, Its Plans Show a Much Different Intent. The Daily Signal.
  20. Google Scholar

  21. Berardelli P (2010) Say Goodbye to Sunspots? Science, Physics. Space.
  22. Google Scholar

  23. Berwyn B (2016) Global CO2 emissions from fossil fuels held steady in 2016.
  24. Indexed at, Google Scholar

  25. Brahic C (2007) Climate myths: The cooling after 1940 show CO2 does not cause warming. New Scientist.
  26. Google Scholar

Citation: Kogan F (2022) 1981-2021 Earth Climate Warming: Contribution of CO2 and Milankovitch Cycle. J Earth Sci Clim Change, 13: 623. DOI: 10.4172/2157-7617.1000623

Copyright: © 2022 Kogan F. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

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