ESA Releases Bad and Good News from Earth's Atmosphere Studies

Carbon dioxide emissions increased in East Asia (right) at an average rate of 9.8% per year from 2003 to 2011, but nitrogen oxides increased by ‘only’ 5.8% per year.  

This indicates a use of cleaner technology in East Asia. 

North America and Europe, however, show slightly decreasing trends for both gases. 

The maps show the corresponding spatial pattern as obtained from the satellite data: red corresponds to regions with high values of NOx and CO2, while blue indicates background values.

Credit: ESA

While Europe and North America show a decrease in emission trends between 2003 and 2011, emissions related to economic growth in East Asia continue to rise, but with a reduction in nitrogen oxides emitted per amount of carbon dioxide.

This demonstrates the use of cleaner technology in East Asia.

Nitrogen oxides are generated during the high-temperature combustion of fossil fuels in automobiles and industrial machinery.

They contribute significantly to a reduction of air quality and can be the cause of respiratory problems.

At the same time, these sources release large amounts of carbon dioxide. Carbon dioxide is toxic only at very high concentrations, but is the most important man-made greenhouse gas, leading to global warming and its related consequences.

In a study published yesterday in Nature Geoscience, scientists from the University of Bremen in Germany used data from the Sciamachy instrument on ESA’s Envisat satellite to measure nitrogen dioxide and carbon dioxide trends from 2003 to 2011.

They also exploited  Sciamachy-based data products generated within the ‘GHG-CCI’ project under ESA’s Climate Change Initiative.

“Nitrogen dioxide has a relatively short lifetime, hours, compared to carbon dioxide, which lasts decades, and is a suitable tracer of recently emitted carbon dioxide from fossil fuel combustion,” explained Maximilian Reuter, lead author of the study.

“Sciamachy measured nitrogen dioxide and carbon dioxide simultaneously. We used a spatial high-pass filtering method to isolate the anthropogenic carbon dioxide signal from overlaying signals due to uptake and release of carbon dioxide by vegetation.”

Satellite-derived CO2 concentrations proportional to local anthropogenic emissions in North America and Europe. 

The green line shows the mean value and the grey-shaded area its variability and uncertainty. 

This indicates that less CO2 is emitted during weekends compared to week days.

Using this method, the scientists were able to better see where and when carbon dioxide was emitted.

For example, it showed that less carbon dioxide from local anthropogenic sources is emitted during weekends in Europe and North America compared to week days.

“This has never been observed from space before and shows how accurate the used method is,” said Dr Reuter.

Although Envisat’s mission ended in 2012, a decade of data from its 10 instruments is still being exploited for studies on Earth’s atmosphere, land, oceans and ice caps.

“Unfortunately, none of the existing nor any of the planned near-future satellites are designed to directly observe carbon dioxide emissions of cities, power plants, volcanoes or other important emission hot spots,” said Michael Buchwitz, co-author of the study and GHG-CCI scientific leader.

“This will only be possible with the proposed mission CarbonSat.”

CarbonSat is one of the two candidates for ESA’s eighth Earth Explorer satellite.

Using the unique spectroscopic fingerprint of carbon dioxide and methane, CarbonSat aims to image these two strong greenhouse gases at very high resolution.

The mission would lead to a better understanding of the sources and sinks of atmospheric carbon dioxide and methane.

ESA budget cuts a major blow to CarbonSat - Earth climate science

CarbonSat Image Credit: Astrium

ESA’s funding shortfall is bad news for CarbonSat, a mission aiming to track atmospheric carbon dioxide.

For Europe’s space chiefs, the outcome of last week’s European Space Agency (ESA) budget negotiations was better than expected, given the continent’s economic troubles.

But for Volker Liebig, ESA’s head of Earth Observation programmes (EOP), there is a sting in the agreement.

The multi-year budget that member states approved — which falls some €2 billion (US$2.6 billion) short of ESA’s proposed spending of about €12 billion — could force him to postpone or cancel a mission aimed at pinning down the mysterious carbon sinks that are slowing the rise of greenhouse gases in Earth’s atmosphere.

Ahead of the budget negotiations in Naples, Italy, on 20–21 November, Liebig had hoped to secure around €1.25 billion for new research satellites.

With France, Italy and Spain contributing much less than expected, he received €1.9 billion for Earth-observation projects.

But €808 million has already been allocated for a new generation of weather-forecasting satellites, leaving him with little more than €1 billion for research missions.

“We have to discuss with scientists in the next few weeks what to do,” Liebig says. “But we will not be able to develop all the science satellites we wanted to.”

Most vulnerable, he says, is a planned €250-million climate-change mission scheduled for launch in about 2018.

One of the two contenders for the mission, CarbonSat, would map atmospheric concentrations of carbon dioxide and methane at high-enough resolution to investigate a long-standing puzzle: why only about half of the CO₂ emitted by human activities remains in the atmosphere.

Scientists assume that the rest is absorbed largely by the oceans and plants, but ground-based monitoring stations are too few and far apart to pinpoint the sinks.

Satellites could fill in the gaps in the picture, but in April ESA lost contact with Envisat, the one satellite providing such data (see Nature 484, 423–424; 2012).

Neither Japan’s existing Greenhouse Gases Observing Satellite nor NASA’s Orbiting Carbon Observatory-2 (OCO-2), scheduled for launch in 2014, will map greenhouse-gas concentrations in as much detail as CarbonSat, which would survey the whole globe with a resolution of 4 square kilometres.

“The information that it would collect is essential for developing, implementing, and monitoring greenhouse-gas-emission policies,” says atmospheric physicist David Crisp of NASA’s Jet Propulsion Laboratory in Pasadena, California, who is the science team leader of OCO-2. “A timely launch of this satellite should be among the highest priorities of ESA”.

CarbonSat’s competitor for ESA funding, FLEX, would also help to pin down carbon sinks, by measuring the faint fluorescence generated by plants during photosynthesis — a measure of how efficiently they absorb carbon.

“The last thing we want to do is to destroy the forests or whatever is absorbing almost half of the CO₂ that we are emitting,” says Crisp.

“Wouldn’t it be good to know where these processes are occurring?”