Research Features

Retrospections: Think Global, Act Local

Recently, Astrobiology Magazine's climate blog, The Hot Zone, spoke with Dr. Anastasia Romanou, Associate Research Scientist at NASA Goddard Institute for Space Studies, about the need for precise local measurements of climate phenomena. Local measurements can provide information about the real impacts of climate change — how weather patterns are changing and how this affects the biosphere at the local level. These are important issues for astrobiologists who seek to understand the drivers and effects of ecosystem change and the future that may be in store for life on Earth.

Satellite image of haze over eastern Chine
The satellite image taken in 2006 shows a thick band of haze over eastern China that stretched from Beijing to beyond Shanghai. (Image: NASA)

In her research and climate modeling, Dr. Romanou does what I'd describe as fitting in with "think global, act local."

She cited, as an example, a study she and her colleagues undertook recently to ascertain the amount of radiative energy that reaches the Earth's surface.

According to measurements made in two very far-flung locales, Dr. Romanou and her colleagues found the level of radiation that reaches the Earth's surface varies greatly from location to location.

Dr. Romanou and her colleagues studied two areas that could not be more different from each other in terms of both physical climate and geopolitical climate: Thessaloniki, Greece and Beijing China. Dr. Romanou used local in situ and satellite measurements of radiation levels in Thessaloniki. She and her colleagues relied on satellite data from Beijing for measurements of radiation levels in China.

Dr. Romanou's measurements revealed that in Thessaloniki, where local government initiated a strict emissions control program almost two decades ago, the level of sunlight reaching the surface was much greater than it was before the control program was put in place. In contrast, in Beijing, where such controls were not put in place until 1996, the amount of sunlight that reaches the surface was found to be far less. China's recent economic boom lead to huge increases in energy consumption and a corresponding increase in air pollution. These factors served to degrade Beijing's already poor air quality.

Curious about why Dr. Romanou's team used satellite data for their analysis of China's air, while they used data collected locally in situ in Greece, to carry out their analysis, I asked Dr. Romanou to explain. "While satellite data tells us about large areas and is in some ways too general – the highest resolution we get from satellite data is a footprint of about a hundred square kilometers — local in situ measurements can also be biased by small scale phenomena. Topography, microclimates, urban or rural environments affect local measurements. So we try to use both sets of data.

Photo of sun obscurred by clouds The level of radiation that reaches the Earth's surface varies greatly from location to location. (Image: C. Calvin, University Corporation for Atmospheric Research)

"Many governmental agencies in Europe and Asia are reluctant to release scientific data from their meteorological institutes to third parties. We had to use what is published in the literature, and data we gathered via satellite."

It turns out that some countries have very tight controls over data which can stand in the way of research and international collaboration. Data having to do with air quality and the efficacy of measures taken to improve it are the most often withheld. Governments that withhold data are concerned that releasing it may incriminate them in in the wake of stringent air quality regulations instituted over the last several years by international bodies.

It seems as though sometimes gathering data about climate presents difficulties that are more about politics than they are about science. Next time, conversations with scientists involved in the Earth Observing System (EOS).


Zerefos, C.S., K. Eleftheratos, C. Meleti, S. Kazadzis, A. Romanou, C. Ichoku, G. Tselioudis, and A. Bais, 2009: Solar dimming and brightening over Thessaloniki, Greece, and Beijing, China. Tellus, 61B, 657-665, doi:10.1111/j.1600-0889.2009.00425.x.

Romanou, A., B. Liepert, G.A. Schmidt, W.B. Rossow, R.A. Ruedy, and Y.-C. Zhang, 2007: 20th Century changes in surface solar irradiance in simulations and observations. Geophys. Res. Lett., 34, L05713, doi:10.1029/2006GL028356.

This article was originally posted on-line as a Astrobiology Magazine "Retrospection" feature.