Climate Change: Global Warming Is Driven By Human Activity, Study Confirms

The European Commission's Joint Research Center recently conducted a study that examined records of man-made carbon dioxide and methane emissions from the last 150 years, and confirmed that these emissions have led to global warming in the past century. Europe, North America, China, Siberia, Africa's Sahel zone and Alaska show signs of the most pronounced consequences of these emissions.

The statistical method used by the researchers allowed them to quantify causalities in order to analyze relationships between greenhouse gas emissions time-series data and air temperatures since 1850, according to a press release. The method used by the team provided results that are impossible to find by using traditional, and time-delayed, correlations between temperature and greenhouse gas emission changes, or by utilizing normal least square regression analysis. Neither of those methods can show casual relations.

The team found that increasing levels of man-made emissions have caused the climate change Earth is seeing in the form of global warming. Further carbon dioxide emissions over time will only lead to further warming, according to the study's authors.

The same technique was also applied to examine historical air temperatures and carbon dioxide/methane data over the past 800,000 years. This data was available due to work from a decade ago, when a 3,000-meter deep ice core was drilled in Antarctica, offers clues on an eight-millennia long time scale.

Using the data from the ice core, the researchers discovered that there is a causal relationship between an increase in temperature and the rise of CO2/CH4 levels - the opposite of what they found for the last 150 years - which confirmed the technique's validity. Due to the ice core data, it's been previously known that an increase in temperature was followed by higher CO2 and CH4 emissions, a causality relationship that appeared to begin reversal around 5,000 years ago.

In the past 150 years, starting with the industrial age, when unprecedented quantities of CO2 began being pumped into the atmosphere, higher temperatures began following the increase in those emissions, instead of the other way around. The causal relationship shifted with the introduction of human influence.

This data not only provides support for models on global climate change, but also shows that further research needs to be carried out in regions where sensitivity to global warming caused by human activities is high, like Europe, North America and China.

Currently, the researchers are unaware as to why there is a high degree of causality seen in Siberia, the Sahel zone and Alaska, where there is less intense human influence. The authors warn that this should become the focus of research to better understand the dynamics of regional climate.

The findings were published in Scientific Reports.

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