Extreme Weather Adds To Warming
August 15, 2013

Severe Weather Events Contribute To Global Warming

redOrbit Staff & Wire Reports - Your Universe Online

Extreme weather and climate events such as heavy precipitation, violent storms, heat waves and lengthy droughts cause terrestrial ecosystems to absorb approximately 11 billion tons less carbon dioxide each year, according to new research appearing in the latest edition of the journal Nature.

That is equivalent to approximately one-third of global CO2 emissions each year, according to an international team of researchers led by Markus Reichstein, Director of the Max Planck Institute for Biogeochemistry in Jena.

Reichstein’s team set out to analyze the impact extreme conditions would have on the terrestrial ecosystem. They used Earth observation methods and numerical models to show how especially extreme droughts lead to a drastic reduction in the carbon sequestration of forests, grasslands, and crop areas.

They reviewed satellite imagery from 1982 through 2011 to reveal how much light is absorbed by plants in different regions for use in photosynthesis. From that information, they were able to determine the amount of biomass an ecosystem accumulated during or after an extreme weather event.

Furthermore, they used data collected from a global network of 500 recording stations to determine how much carbon an ecosystem absorbs and releases in the form of CO2. That data was then input into complex computer models to calculate the global impact of extreme weather on the carbon balance, and found vegetation absorbs an average of approximately 11 billion fewer tons of carbon dioxide than they would in extreme weather-less climate.

“This reduction in the regional and global carbon uptake has the potential to influence the global climate,” explained the Helmholtz Association, a Berlin-based research organization. “Especially large scale events like the heat wave in western and southern Europe in the year 2003 provide the evidence that such extremes events have a much stronger and long lasting impact on the carbon cycle than expected so far.”

In 2003, the heat wave experienced by those regions of Europe became one of the first large-scale extreme weather events that could be documented in detail by scientists. They tracked how heat and drought affected the exchange of carbon dioxide between Earth’s ecosystems and the atmosphere (better known as the carbon cycle).

The data they collected indicates the extreme weather events had a far greater impact on the carbon balance than experts had previously believed, the researchers said. They noted it is possible that phenomena such as droughts, heat waves and heavy storms weakened the buffer effect exerted on the climate system by terrestrial ecosystems. Over the past five decades, plants and soil have absorbed up to 30 percent of the carbon dioxide produced by fossil fuels and other man-made sources.

The researchers plan to conduct additional research to further enhance their understanding of the potential consequences of extreme weather. Specifically, they said they are looking to simulate the way that different types of ecosystems respond in both laboratory and field-based experiments. Their current study, however, demonstrates extreme weather can have far-reaching consequences.

“As extreme climate events reduce the amount of carbon that the terrestrial ecosystems absorb and the carbon dioxide in the atmosphere therefore continues to increase, more extreme weather could result,” Reichstein said. “It would be a self-reinforcing effect.”