Climate science

First look at new NASA satellite map reveals global carbon dioxide hotspots

  • 18 Dec 2014, 20:10
  • Roz Pidcock

NASA space scientists today unveiled a new satellite map showing carbon dioxide levels in the atmosphere right across the globe.

The map is the first two months of data from the new Orbiting Carbon Observatory-2 (OCO-2) mission, launched in July this year.

The team from NASA's Jet Propulsion Laboratory, Colorado State University and California Institute of Technology presented their findings at AGU conference in San Francisco today.

PIA18934

The map shows an average global concentration of 400 parts per million (ppm) with hotspots of high carbon dioxide in the Southern Hemisphere above southern Africa and Brazil. The scientists attribute this to springtime burning of savannas and forests to clear land for farming. 

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What do squirrels, beavers and reindeer have to do with methane emissions?

  • 18 Dec 2014, 15:44
  • Robert McSweeney

It's not just humans that are causing climate change. Squirrels and beavers have both been implicated in recent days as research reveals their contribution to the release of methane, a powerful greenhouse gas.

Obviously the Internet loves a good rodent story. But could it really be the case that these toothy animals are paving the way to climate catastrophe?

It's unlikely, an expert tells us, but that's not to say they should be overlooked.

Global methane emissions

Methane is a powerful greenhouse gas, around 25 times more effective at trapping heat than carbon dioxide over the course of a century. About a fifth of the global warming linked to human activity is as a result of methane emissions, scientists estimate.

The sources of methane emissions are shown in the figure below. Total emissions from human activities, such as farming livestock and burning fossil fuels, are similar to natural sources, the largest of which is from decomposing vegetation in wetlands.

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Deforestation in the tropics affects climate around the world, study finds

  • 18 Dec 2014, 10:00
  • Robert McSweeney

"The effects of tropical deforestation on climate go well beyond carbon," says Professor Deborah Lawrence, "[it] causes warming locally, regionally, and globally, and it changes rainfall by altering the movement of heat and water."

These are the conclusions of a worldwide study into the deforestation of tropical rainforests, which shows that cutting down trees can have immediate impacts on the climate and put agricultural productivity at risk.

Rainforests are more than just a carbon store

Deforestation and land use change account for approximately 11 per cent of global carbon dioxide emissions. But the new research finds that cutting down trees doesn't only affect the carbon they lock up.

The research, published in Nature Climate Change, reviews academic studies on deforestation of tropical rainforests in the Amazon basin, central Africa, and southeast Asia. Many of the studies use climate models to simulate what happens if you remove these forests completely, and they suggest that deforestation in the tropics can affect the climate on the other side of the world.

The map below shows how far-reaching some of these potential impacts are. The triangles show areas where rainfall is expected to decrease because of tropical deforestation, and the circles show areas of increase. The colours indicate the link to where the deforestation occurs.

So the models suggest deforestation in the Amazon, for example, can reduce rainfall over the US Midwest and even in northeast China. Deforestation in central Africa can cause a drop in rainfall in southern Europe, and loss of trees in southeast Asian can bring wetter conditions in southern Europe and the Arabian Peninsula.

Lawrence & Vandecar (2014) Fig1

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