international analysis and commentary

What we really know about climate change


In 1988, the US Congress hearings on the anthropogenic origin of climate change, and on the necessary actions against it, had astonishing success. Not by chance: one of the worst heat waves of all times had recently hit the US and the number of deaths it caused raised the public concern over a matter that, otherwise, would likely have been ignored.  Public opinion needed this as at the time the consensus among scientists was not clear and explicit, climate change had little or no space in the media, and fossil fuel companies had been financing misinformation campaigns for years (as disclosed, for instance, by the Union of Concerned Scientists).

Now, 27 years later and as the Paris “COP21” (the 21st “Conference of Parties”) is underway in the hope of reaching the first, legally binding and global agreement on climate change, the situation is different: we know more about climate change as a phenomenon, we have a clearer picture of its effects and, most of all, we know about the level of awareness the global audience has. This knowledge is a tool which, if adequately used, can help develop a sustainable solution to address climate change.

First, it is now clear that climate change is happening. The most evident fact is that the Earth is warming: data from NASA show that, in July 2014, we were at 0.75 degrees Celsius above the 1951-1980 average. The medium yearly temperature has kept increasing steadily since the late 1970s, and a general trend of increment dates back to the early 20th century. This phenomenon is also proved by the change in the amount of Arctic ice, which decreased by more than 10% in the past 34 years, or by the 3.22mm the sea level has gained since 1993. However, the effects of climate change go beyond the mere warming and influence, for instance, the precipitation extremes, whose 18% could now be attributed to climate change.


Global emissions from 1892 to 2013. Source: CDIAC, 2015

It seems then hard to believe the words of eminent climate deniers (some of whom are influential public figures, such as US presidential hopeful Donald Trump), when the ten hottest years ever recorded happened in the past 17 years. This correlates with the sharp increase in emissions, which the world has seen from the 1950s and which brought the CO2 concentration to 30% more than the highest historical average before that period. Of course, some countries are much more responsible than others for such increases: the World Resource Institute reports that, from 1990 to 2011, the US, China and the EU have been responsible for 43% of global emissions. Considering emissions from 1850 to 2011, the EU and the US alone account for 52% of the total. Values per capita are even more astonishing: despite tripling their level from 1980 to 2011, emissions per capita in China are now almost at the same level as in Italy, but still one third of those in the US. Emission intensity (emissions per GDP) has a great variability depending on whether land use is included or not: Brazil is well below the world average if land use is not considered, and almost at the same level when this factor is added to the indicator. Indonesia, which has the unfortunate world record for deforestation, has the greatest emission intensity in the world, when land use is taken into account.

Paradoxically, some of the countries that objectively bear most responsibilities for climate change have the greatest share of climate deniers (or “skeptics”, depending on which side of the debate you are on). In a 2015 Pew Center survey, seven out of the ten top emitters appeared not to consider climate change as the most important global threat. Another 2014 survey by Chatham House, reported by the news website Carbon Brief, reported that the share of US citizens who do not believe in the human origin of climate change is seven times higher than that of China. In the BRIC countries, it is slightly more than a third than those of Poland, and half than Japan. Google trends are interesting to analyze as well: countries with a high emissions levels, such as the UK or the US, rank well below Fiji, Ethiopia or Malawi for Google searches on climate change. In the same way, London is significantly below the number of searches of Nairobi or Manila, as are Ottawa, Sidney and Washington. In a 2015 analysis by the Google Lab Trends, the phrases associated to global warming related searches show the same trends: in the top three for New York we find “if there is global warming, why is it so cold?” and in London “is global warming real?”

Despite skepticism and denial, action against climate change is not impossible, especially if we consider the causes. As a matter of fact, 81% of global emissions in 2012 were caused by energy production, out of which more than 50% came from electricity generation. In fact, climate action is not just possible, it is necessary. In 2006, the Stern Review predicted a 5% to20% loss in global GDP if no action was taken against climate change, with a temperature rise by 5 or 6 degrees by 2100. The Economist Intelligence Unit recently estimated 4.2 trillion dollars in damages to the private sector in the world by the same year, if the temperature increase will stay below 2 degrees. The figure is 7 trillion in case of an increase by 5 degrees. Meanwhile, The Lancet foresees 2 billion more people exposed to heavy rains and 1 billion more exposed to floods, along with the resulting increase in threats to global health, if emissions will not be reduced.

If what we know about climate change is extremely alarming, it is what we do not know that should frighten us the most. Politically, because despite the recent diplomatic action by, for instance, China and the US, their climate pledges to the UN (the so-called “Intended Nationally Determined Contributions” – INDCs), are far from optimal. China does not foresee an immediate reduction, but first an emission peak by 2020. The planned US decrease is far slower than that projected for the EU (which is already more advanced on the path towards decarbonization). The Russian 108,212.05 Mton of CO2 reduction from 2012 levels is a sort of fake commitment if we consider the forecasted slowdown of the Russian economy. Overall the think tank Carbon Tracker estimates that the pledges finalized right before the beginning of the Paris Conference will only limit the increase in temperature by 3 degrees in 2100, assuming they are fully implemented. By now, even that outcome is not granted: current policies will likely result in a 3.6 degrees increase.

An additional danger is due to the level of scientific uncertainty surrounding estimates and forecasts. Many of the effects influencing the impact of climate change – and particularly their combination – are largely unknown. The impact of the global amount of snow, ice, forest or desert cover in reflecting the light, and in increasing or decreasing global warming, is still unclear. We even have extremely variable estimates of the total amount of trees, and so of deforestation. We know we are facing the greatest threat the Earth has ever seen, yet we do not how big it really is. Bearing this in mind, the COP21 will hopefully leave as its legacy a Socratic exercise and a humble attitude: we know that we do not know – or do not know enough. This is the best way to overcome the political “short-termism” and myopic national interests that will hinder efforts to find a practical solution to our planet’s big problem. And this is what we should truly know.