US China Top Global Warming List
January 17, 2014

US And China Top Global Warming List, But Not All Emitters Are Equal

Ranjini Raghunath for - Your Universe Online

In a finding that comes as little surprise, the United States and China were found to be among the top seven countries that contributed to global warming in the last century.

The study, carried out by scientists at the University of Concordia, also added Russia, Brazil, India, Germany and the United Kingdom to that list. Taken together, these countries were responsible for up to 60 percent of global warming between 1906 and 2005, they report. That accounts for 0.7 degree Celsius of the 0.74 degree Celsius total global temperature rise.

The study was published in the journal Environmental Research Letters.

The United States was the highest contributor, responsible for a global temperature rise of 0.15 degree Celsius – more than 20 percent of the total observed global warming.

“The United States is an unambiguous leader, with a contribution of more than double that of China, which falls second in the ranking,” the authors wrote.

Russia came next, with an 8 percent contribution, followed by Brazil and India tied at seven percent, and the UK and Germany at five percent each.

“There are vast disparities in both total and per-capita climate contributions among countries,” the authors wrote. “Across most developed countries, per-capita contributions are not currently consistent with attempts to restrict global temperature change to less than 2 °C above pre-industrial temperatures.”

The findings were based on analysis of carbon dioxide emissions from fossil fuel burning and land-use change, as well as emissions of other noxious gases such as methane, nitrous oxide and sulphate aerosols, from the year 1750 onwards. Contributions were calculated based on the lifetime of these gases in the atmosphere, which determines the level of damage they can cause.

The authors also tried comparing the proportion of emissions with the size of the country’s landmass. They found that, for instance, although China and Brazil are among the top greenhouse gas emitters, their landmass is huge and their emissions correspond more or less to what would be normally expected from countries of their size.

Countries like the US, India and Japan, on the other hand, give out emissions alarmingly in excess of what would be expected for the size of their respective landmasses.

In a third consideration, the authors tried to put emission levels in the perspective of individual countries’ populations. By that measure, China and India fell to 19th and 20th positions, appearing to contribute much less considering their billion-plus population. By contrast, the United States and England topped that list.

"It was surprising to see some of the less-industrialised countries (such as Brasil) with such high rankings, but this also reflects their CO2 emissions related to deforestation," said lead author Damon Mathewst.