By guest blogger .
I.4 Other consequences of CO2 concentration and temperature increase
I.4.1 Consequences of temperature increase
In the Netherlands, or Western Europe, it is not unusual for the difference between daily maximum and minimum temperatures to be more than 10°C. Nobody finds this strange or dangerous. But according to the media, the earth will irrevocably break down if an average of 1.5°C to 2°C is added. This seems strange because in the (distant) past, such and even higher temperatures prevailed on earth. And yet there were no tipping points…
Figure 2 : Temperature and CO2 concentration from 600 million years ago to the present Source
Late Carboniferous to Early Permian time (315 mya — 270 mya) is the only time period in the last 600 million years when both atmospheric CO 2 and temperatures were as low as they are today (Quaternary Period) . Temperature after CR Scotese http://www.scotese.com/climate.htm CO2 after RA Berner, 2001 (GEOCARB III)
For long periods, the temperature on Earth was 20 to 25°C, while now it is only about 15°C. It is now about 10°C colder than it has been for most of the time that the Earth has existed. There was also much more CO 2 in the past , 1000 to 7000 ppm. It is not surprising that the temperature is so low, because we are still living in an ice age :
“ An ice age is a period in which ice caps occur on land. The presence of ice caps on Greenland means that we are by definition living in an ice age . ”
Should one be concerned about a degree more? If one looks at the past, there is little reason to be; the normal temperature on Earth seems to be between 20°C and 25°C. This also means that there can be no tipping points below 25°C, because they have not occurred in the past. The temperature will probably return to somewhere between 20°C and 25°C, the normal temperature. There are advantages to that one degree more, by the way.
I.4.1.1 Fewer climate deaths
The climate always fluctuates, but has remained virtually unchanged since 1850. There are now only slightly milder average temperatures. But even this small average temperature increase results in fewer “climate deaths”. This is because it is mainly the minimum temperatures that are rising, so the average is also slightly higher. Many more people still die from the cold than from the heat.
From a study of deaths in England and Wales:
“Our analysis indicates that the excess in mortality attributable to cold was almost two orders of magnitude higher than the excess in mortality attributable to heat.”
Excess mortality due to cold temperatures was 32 times higher than from heat in Switzerland from 1969 to 2017.
“Total all-cause excess mortality associated with nonoptimal temperatures was 9.19% [95% confidence interval (CI): 7.72, 10.47], which translates to 274,578 (95% CI: 230,657, 312,761) temperature-related excess deaths in Switzerland between 1969 and 2017 (Table 2; Table S4). Cold-related mortality represented a larger fraction in comparison with heat , with 8.91% (95% CI: 7.46, 10.21) vs. 0.28% (95% CI: 0.18, 0.37).”
Excess mortality due to cold was 42 times higher than for heat in China in 2019.
“We estimated that 593·9 (95% UI:498·8, 704·6) thousand deaths were attributable to non-optimal temperatures in China in 2019 (PAF=5·58% [4·93%, 6·28% ]), with 580·8 (485·7, 690·1) thousand cold-related deaths and 13·9 (7·7, 23·2) thousand heat-related deaths.”
Excess mortality due to cold temperatures was 12.8 higher than that due to heat “across 612 cities within 39 countries over the period 1985–2019.”
“Here, we perform a comprehensive assessment of temperature-related mortality risks using ground weather stations observations and state-of-the-art reanalysis data across 612 cities within 39 countries over the period 1985–2019. … In general, across most countries, the estimates of the excess mortality are very similar, with a global-level excess of 0.53% (95% eCI 0.50–0.56) versus 0.49% (0.43–0.53) for heat, and 6.02% ( 5.80–6.18) versus 6.25% (6.05–6.41) for cold, from ground stations and ERA5-Country data, respectively (‘Global’ in Fig. 5 and Table S3). These percentages correspond to 357.729 ( 95% eCI 335.138–376.498) versus 326.032 (288.069–357.247) for heat , and 4,030.793 (3,880.068–4,137.579) versus 4,186.014 (4,051,321–4,293,311) for cold .”
Global warming reduces “climate deaths” because about 11 to 13 times more people die from cold than from heat.
I.4.1.2 Higher crop yield
Not only does the number of climate deaths decrease, but there is also a positive effect on plant growth in general. This is especially important when growing food crops.
“The results revealed that the CO 2 -induced increase in grain number and grain yield was higher in combination with a temperature level of 21–25 °C as compared to lower levels (< 15 and 16–20 ℃ ) .”
and
“An increase in atmospheric CO 2 generally exerts beneficial effects on plant biomass by increasing net photosynthesis by 30 to 50% and reducing photorespiration (Drake et al. 1997 ; Poorter and Navas 2003 ; Schapendonk et al. 2000 ). This has been studied for cereals including barley, wheat, rice, oat, and rye ( Conroyac et al. 1994 ; Kimball et al. 2002 ; Long et al. 2006 ).Chen and Sun, 2024 :
“…, while the main factor that really affects China’s crop yield directly is the local air temperature change. When the air temperature in China is high , the yield will show an increasing trend, and vice versa.”
Figure 3 : Increase in world food production, source
The graph above, figure 3, shows that there is a continuous increase in world food production. The yield is increasing partly due to the “CO 2 fertilization”
A higher temperature therefore has beneficial effects on greening and world food production.
I.4.2 CO 2 concentration increase
I.4.2.1 Is CO2 “ dangerous”?
CO2 is not a “pollutant” or toxic substance, as some people, including the media, claim. The concentration in air exhaled by humans contains up to 40,000ppm CO2 . From https://www.cdc.gov/niosh/idlh/124389.html : “ It has been reported that submarine personnel exposed continuously at 30,000 ppm were only slightly affected, provided the oxygen content of the air was maintained at normal concentrations [ Schaefer 1951 ]. ” The “Occupational Safety and Health Administration” “Permissible Exposure Limit” (OSHA PEL) is a legal safe limit at which work is allowed and is currently 5000ppm in the US, 12x higher than the current concentration in the atmosphere.
CO 2 is the building block par excellence of all life on earth. Plants breathe in CO 2 and use it to produce all kinds of substances that are essential for their life. When there is a shortage of CO 2 , plants die. And consequently also the herbivores and eventually also the carnivores. That is why CO 2 is essential for life, also for humans.
I.4.2.2 The earth becomes greener, higher crop yields :
In an article from NASA: https://www.nasa.gov/centers-and-facilities/goddard/carbon-dioxide-fertilization-greening-earth-study-finds/
there is a short film about how the earth is becoming greener due to increased CO2 concentration , helped by higher temperatures. It refers to a study by Zhu et al, 2016
“ CO 2 fertilization effects explain most of the greening trends in the tropics , whereas climate change resulted in greening of the high latitudes and the Tibetan Plateau. LCC contributed most to the regional greening observed in southeast China and the eastern United States. ”
“Besides, CO 2 is an essential element of crop photosynthesis and a major climate change scenario construction indicator. Increasing CO 2 concentration in the Earth’s atmosphere can increase the photosynthetic rate of crops, which directly stimulates crop growth and increases the dry matter content, resulting in increased food production ( Lawlor & Mitchell, 1991 ; Wang et al., 2014b ; Ziska & Bunce , 2007 ).
“Warmer temperatures and more CO 2 will mean more food at a lower price for nearly everyone,…”
(text can also be viewed here: https://andymaypetrophysicist.com/wp-content/uploads/2024/05/Carbon-Dioxide-and-a-Warming-Climate-are-not-problems_Final_Submission_no_logo.pdf )
A higher CO2 concentration , together with a higher temperature, provides more green and more food (figure 3). This is favourable, given the increase in the world population.
I.4.2.3 Other effects of higher CO2 concentration
I.4.2.3.1 Better water management
“ The CO2 fertilization effect has benefits for both vegetation growth and water use efficiency (WUE).”
and
“…elevated CO 2 concentrations could indirectly enhance water availability by improving [water use efficiency]… reducing vegetation water demand .”
and
“The relationship between vegetation growth and water availability (referred to as Rvw), representing vegetation responses to water availability, is a key metric for understanding vegetation responses to drought under climate change ( Shi et al 2021 , Zhao et al 2021b , Chen et al 2022 , Smith and Boers 2023 ). Over the past few decades, global vegetation growth has been observed to increase, a phenomenon known as ‘greening’ ( Myneni et al 1997 , Zhu et al 2016 , Huang et al 2018 , Piao et al 2020 ). The vegetation greening trend, attributed to factors such as the carbon dioxide (CO 2 ) fertilization effect, climate warming, and human activities, has been widely studied ( Piao et al 2015 , 2020 , Lu et al 2016 , Zhu et al 2016 )”
and
“The CO2 fertilization effect has benefits for both vegetation growth and water use efficiency (WUE) ( Lu et al 2016 , Humphrey et al 2018 , Wang et al 2020 , Hsu and Dirmeyer 2023 )
I.4.2.3.2 Cooling or less warming
“ Our findings illuminate Earth greening’s potential to mitigate hot temperature extremes , offering a pathway toward more resilient and sustainable climate adaptation and mitigation. ”
“According to satellite observations, the earth has been experiencing widespread vegetation greening since the 1980s, primarily due to large-scale climate change and CO 2 fertilization effects 1,2 . Such greening could mitigate global warming by triggering negative biochemical feedback to the climate system, which refers to increasing CO2 removal from the atmosphere through the vegetation photosynthesis process 3–5 .”
and
“ Vegetation greening in dry and warm regions significantly cools the land surface ,
and this cooling diminishes and reverses to the warming effect with gradually decreased temperature or increased precipitation (Fig. 1b).”
“ Here, we provide the first observational evidence of the greening effects on SAT and SAT extremes in China during 2001–2018 using the ‘space-for-time’ method. The results show a negative SAT sensitivity to greening (–0.35 °C m 2 m –2 ) over China and a cooling effect of −0.08 °C on SAT driven by vegetation greening during the study period. Such a cooling effect is stronger on high SAT extremes, particularly over arid/semiarid areas, where greening could bring an additional cooling of −0.04 °C on the hottest days. An attribution analysis suggests that the main driving factor for the cooling effect of greening is the evapotranspiration change for arid/semiarid regions and the aerodynamic resistance change for humid regions. ” (SAT = near-surface air temperature)
Summary
The earth is becoming greener and the cause of this is an increase in the CO 2 concentration and the temperature. This greening has a favourable effect on the temperature and results in less warming or even cooling. Partly due to the improved water management of all plants, there is a favourable effect on evapotranspiration. This reduces the risk of droughts.
Check: Claim (5) “It is assumed that an increase in those two, temperature and CO2 concentration , would be harmful(5).” is completely wrong. There are almost only beneficial effects associated with both the increase in CO2 concentration and the increase in temperature. One may wonder why governments want to take “climate measures”? After all, there is nothing wrong with the climate. One could even claim the opposite.
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To be continued.
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