In a paper published last month, 11 Chinese climate scientists note that the Earth has experienced "widespread vegetation greening" since the 1980s due to CO2 fertilisation effects. Such greening could mitigate global warming "by triggering negative biochemical feedback to the climate system". The darker green vegetation absorbs more of the sun's heat, claim the scientists, while processes involving water evaporation or heat convection between the surface and the atmosphere also depress local temperatures.
The Earth has undoubtedly greened over the last 40 years as atmospheric levels of CO2 have started a slow recovery from what some scientists claim is a period of dangerous collapse. The current level of CO2 in the atmosphere is around 419 parts per million and is near an all-time low in the paleo record. In the past, levels have been up to 20 times higher but below about 180 ppm, plant and human life would start to die. It is generally accepted that there has been a recent increase in global vegetation of around 14%. In 2016, a major international scientific study involving 32 scientists noted there had been a "persistent and widespread increase" in growing season greening over 25-50% of the global vegetated area. Some scientist are relaxed about rising levels of CO2 as a consequence. Dr Roy Spencer, the former senior scientist at NASA, notes that, "though CO2 is necessary for life on Earth to exist, there is precious little of it in Earth's atmosphere".
The Chinese study estimated temperature response to higher levels of vegetation between 2001-2018 by examining satellite temperature recordings and records of leaf area data. Other matters considered included local climate conditions, plant types and annual and seasonal factors. An estimated signal was then compared with historical temperatures records "to evaluate the potential climate benefits of greening at global and regional scales".
On a wider level, this paper is an important contribution to the debate over climate change and the contention that human-caused CO2 is the main control knob for any recent warming in the atmosphere. Over 600 million years, CO2 has been gradually drawn out of the atmosphere and sequestered in the Earth's crust. The problem with the hypothesis of anthropogenic warming - other than lack of any actual proof - is that it fails to provide much correlation between temperatures and CO2 levels in the current, historical or paleo past. Arguments that the gas becomes 'saturated' at certain levels, and its warming properties reduce on a logarithmic scale, can provide a more convincing explanation to fit past observations.
Away from the 'settled' science narrative - a political fiction designed to stifle debate and promote Net Zero - scientists research the many influences that cause the climate to change. It is highly improbable that increasing CO2 in the atmosphere will cause a climate 'breakdown' because it has never done so in the past. The atmosphere is a chaotic, non-linear place, and numerous influences including heat exchange and ocean currents play a very important part. The climate also appears to have self-regulating checks and balances - atmospheric CO2 boosting plant growth, which in turn cools the local surface environment, being just one of many.
Chris Morrison is the Daily Sceptic's Environment Editor.