Climate changes do not jeopardize Earth’s existence

The rapid increase in the temperature represents a greater threat to humanity than the planet, estimates Ulrich Glasmacher.

By Elton Alisson, Recife

Agência FAPESP – The rapid increase in the Earth’s temperature represents a greater threat to humanity than to the planet, which has survived several periods of climate change.

This is the opinion of climatologist Ulrich Glasmacher, a professor at the University of Heidelberg in Germany, who made the comment in an address on the geological and social aspects of global climate change last week in Recife (PE) during the 65th Meeting of the Brazilian Society for the Progress of Science.

According to the German researcher, the planet has been undergoing cold periods followed by heat waves for more than 450 million years. “The Cretaceous (for more than 100 million years), for example, was one of the hottest periods on the Earth in the last 600 million years,” says Glasmacher.

The levels of CO₂ emissions in the atmosphere at that time were also high, as observed in studies of fossils of ants – an insect that breathes air and expires oxygen, retaining a higher level of CO in its body than humans – explained the researcher.

There is little data, however, about the activity of the sun during that period and its influence on temperatures on Earth. Such data could offer clues about the planet’s climate in the future, said Glasmacher. “What we can say is that every time that there is a very cold period [of glaciation] on Earth, it has been succeeded by a very hot period,” he affirmed.

“The climate changes the Earth has experienced, however, have not put its existence at risk and did not cause the mass disappearance of species,” stressed Glasmacher.

According to him, none of the mass extinctions that have occurred on the planet were caused by climate changes but rather by volcanoes, changes in tectonic plates, meteorites and comets. In all cases, the planet survived.

“Any scenario forecast as fatal for the planet is false and has the objective of causing fear. As devastating as climate change can be, life and the planet will survive without us humans,” he said.

“The planet has survived this in the past, when dinosaurs were extinct, and life on Earth continued in the millions of years afterward. The question, now, is if humanity will manage to survive global climate change,” he pondered.

Risk of extinction

In the opinion of Carlos Nobre, the Secretary of Policy and Programs and Development at the Ministry of Science, Innovation and Technology, the risk that climate change will lead to the disappearance of humankind on the planet is, in fact, very small, because humans have developed cognitive capacities that have made the species the most adapted and adaptable on Earth.

Furthermore, it is very improbable that the concentration of oxygen on the planet will change in the next few years due to the effects of climate change to the point of threatening life on the planet.

The problem is that plants can only conduct photosynthesis at temperatures below 48 degrees Celsius. If the average continental temperature reached this level, there would be a risk of mass extinction of species because of the break in the food chain, stresses Nobre, who spoke at the same conference as Glasmacher.

“It is not that the average temperature on Earth will reach more than 40 degrees Celsius. However, if this happens, there will be a risk of interrupting plant photosynthesis and, as a result, the planet would be very different from today, with fewer life forms and more desert-like conditions – although desert plants do undergo photosynthesis in a shorter period of time,” said the researcher, who is a member of the coordination team for FAPESP’s Research Program on Global Climate Change (PFPMCG).

According to Nobre, the greatest concern about the possible impacts of global warming observed in the anthropocenic period, however, is not related to the final value of the temperature that the species can withstand but rather the speed with which change is occurring, which could make it difficult for several species to adapt.

“Having a five degree variation over 200 years, as we are seeing now in the Anthropocene, is something very rare and has not occurred in many years. Many species do not have conditions to adapt to climate change that quickly,” affirmed Nobre.

“If the temperature took a million years to rise five degrees, the species extinctions would be limited. However, if this happens in a period between 50 and 100 years, extinction will be very widespread. And if it happens in a 30-year period, 40% of the species would be extinct – which, perhaps could not be considered mass extinction, but is a disturbance of a dimension that only volcanoes and meteorites have caused in the past,” he noted.

IPCC Report

Nobre, who is a member of Group 2 of the Intergovernmental Panel on Climate Change (IPCC) confirmed that part of the entity’s fifth evaluation report, entitled AR5, will be published this year.

“The first report of Group 1 will be this year, whereas the reports from Groups 2 and 3 will be released in 2014,” Nobre commented.

“At the end of September, there will be a meeting to approve the Summary for Policymakers,” explained the researcher, referring to the brief prepared especially for public policy makers.

Work Group 1 evaluates the scientific aspects of the climate system and the phenomena of climate change. Group 2 examines the vulnerability of human and natural systems impacted by climate change and the consequences of these alterations and seeks ways to adapt to them.

Work Group 3, on the other hand, evaluates the potential to mitigate climate alterations and limit greenhouse gas emissions.