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By the end of the sixties climate scientists are far from a consensus about the scale and underlying mechanisms driving the change in climate which is taking place. Yet, there’s two things that are becoming very clear: carbon dioxide has an important impact on it and humans are pushing the atmospheric CO2 levels up to unseen values.

The greenhouse effect has been detected, and it is changing our climate now.

1972 First UN environment conference ever taking place in Stockholm. The focus lies on chemical pollution and whaling, climate change is addressed shortly. The Unep (United Nations Environment Programme) is created.

1987 Montréal Protocol is agreed to restrict the CFCs which damage the ozone layer. The agreement shows that political agreement over international planetary action is possible. Today scientist have shown slow but steady recovery of the ozone layer.

1988 James Hansen, climate scientist at NASA, bears testimony over the scientific findings: “The Earth is warmer in 1988 than at any time in the history of instrumental measurements. There is only a 1 percent chance of an accidental warming of this magnitude…. The greenhouse effect has been detected, and it is changing our climate now.”

Hansen’s historical testimony in US Senate

1988 Intergovernmental Panel on Climate Change (IPCC) is founded. They provide reports which give insight in the current climate change models and predictions. The reports are the reference for policy makers.

1992 Earth Summit in Rio de Janeiro, where governments agree the United Framework Convention on Climate Change. Countries agree to bring their emissions back to 1990 levels. Till today 1990 is commonly used as reference base for emissions.

1997 Kyoto Protocol is adopted in Kyoto, Japan. Based on the premise that climate change is real and driven by human carbon dioxide emissions, developed nations agree to cut emissions by an average 5% starting from 2005. Yet the US and China, among the biggest polluters, don’t ratify the agreement.

Many see Earth Summit 1992 as the beginning of worldwide climate policy

1998 Warmest year on record at the time. Scientists still debate whether it is due to climate change, El Nino or both.

2007 IPCC fourth assessment report says it more than 90% sure that humanity is responsible for modern day climate change.

2008 Barack Obama promises to make Global Warming as one of his key working points. Seven years later, not much has been done. Giving his fiat for fracking of shale gas all over the US, he even opens the door to a welcome excuse for fossil fuel companies to wait a bit longer with renewables. Yet, only recently he vetoed the Keystone XL pipeline. This ensures a lot of oil is kept in the ground – where it should be.

Barack Obama made climate change one if his top priorities – not much has been done

2009 Not long before the long-anticipated climate talks in Copenhagen, emails of climate scientists, some of which working for the IPCC, are published on the internet. Sceptics use them to put the climate scientists in bad light and accuse them of lies and fraude. Eight independent communities are founded by different countries in order to investigate the accusations – none of them turn out to be true.

2009 UN Climate Summit in Copenhagen. Expectations are high to find a post-Kyoto international agreement on climate change, but no binding results are reached. When the end of the conference is approaching without any binding deals, climate activists desperately try to get into the building where the world leaders are gathered. It comes to a severe clash with riot police.

2010 European Parliament approves Europe 2020, a ten-year strategy to reduce greenhouse gas emissions by 20% relative to 1990 levels, 20% increase in energy efficiency, and a share of 20% of renewable energy sources in total energy consumption.

Barosso presents the Europe 2020 deals: a bold plan to make Europe world leader in sustainable energy

2013 For the first time the concentration of CO2 in the atmosphere has reached the 400ppm level. 350ppm is regarded as the upper safe level.

2014 The new IPCC report based on more than 900 peer reviewed articles says 99% of scientists agree that modern-day climate change is due to mankind emissions. They outline 5 scenarios and the concept of the carbon budget. To keep warming under 2°C we must start reducing emissions drastically in the next decade or we will simply be too late.

2014 People’s Climate March in New York: an estimated 311 000 people gathered in what became the biggest collective action for the climate in history. The march was intended to urge political leaders, who would arrive a few days later for a climate top in the Big Apple, to take action on climate change.

The People’s Climate March was the biggest collective action for the climate in history

2014 China and US announce together to cut their emissions. An important symbolic step.

2014 Europe makes bolder plans for 2030 than the earlier agreed 20-20 deal.

2014 Climate summit in Lima, Peru, shows once again the deep division between developed and developing nations (see this earlier post). An historical agreement is reached where all nations present promise to cut emission (but still no binding numbers). Everyone puts his hope on Climate Summit in Paris 2015, seen as the last moment we can change the course before it’s too late.

2015 2014 is officially declared as being the warmest year on record. This time there’s no El Nino to blame. Journalism group Climate Central puts it like this: the odds of such a year happening by chance rather than due to a combination of man-made pollution and natural climate variability are less than 1-in-27 million (read also this post).

Main source:

http://www.bbc.com/news/science-environment-15874560

Did you think climate science is a novelty? Not at all. From the 19th century on, mathematicians, physicists, engineers and other smart people have been looking for answers to the most complicated questions regarding Earth’s carbon and energy cycles. A short overview of how the science has grown over the years and finally became a base to policy making as well.

1824 French mathematician and physicist Fourier is the first to describe what we now call the greenhouse effect. He reasoned that there should be a way how Earth keeps part of its warmth it receives from the Sun. Otherwise Earth would be an ice planet and life as we know it would be impossible. He predicts that certain gases in the atmosphere keep some of the infrared radiation from going into space and thus keep the planet warm, like a blanket.

Fourier

1861 Irish physicist and chemist Tyndall finds in experiments that water vapor and carbon dioxide are the most important gases that can trap heat in the way Fourier predicted.

Tyndall

1896 By looking at Earth’s temperature and its links with volcanic eruptions, Swedish scientist Arrhenius reasons that carbon dioxide fluctuations in the atmosphere are responsible for climate change rather than the daily fluctuations in water vapor. Together with his colleague Högbom he finds that industrial-age coal burning will enhance the natural greenhouse effect. Today’s scientists have shown that roughly one out of four CO2 molecules in the atmosphere was put there by humans (they do this with a C14 isotope tracer method).

Arrhenius

1938 Callendar shows that temperatures have risen over the previous century, based on measurements of 147 weather stations. He makes the connection with the available CO2 data. He calculates that doubling the CO2 levels would mean a temperature rise of about 2°C and he also predicts that higher temperatures could trigger a self-sustaining warmer climate (nowadays called the feedback loops). He also addresses the common objection against Arrhenius’ theory that oceans would absorb most of the emitted carbon dioxide by looking at the saturation of CO2 in sea water.

1958 There is still no consensus between scientists over the question whether atmospheric CO2 levels are really increasing or that most of it is absorbed by the sea. Therefore Keeling starts systematic measurements of atmospheric CO2 at Mauna Loa in Hawaii and in Antarctica. Four years later, he delivers the first undeniable proof that atmospheric CO2 concentrations are rising, presented in his famous Keeling curve (the saw tooth form is caused by the seasonal fluctuations in CO2). The match with temperature change (corrected for volcano eruptions) is stunning.

Keeling and his famous Keeling curve

From this moment on, many teams of scientist from around the world start researching climate change via ice cores, air and sea temperature measurements, acidity of ocean measurements… Step by step the old objections are answered, yet until today not all of them have been addressed. Now the science becomes clearer and more frightening, some policy makers start to worry too. It’s the beginning of climate change as a political issue. More about that in the second part of this issue!

Main sources:

http://blogs.scientificamerican.com/plugged-in/2013/05/16/why-we-know-about-the-greenhouse-gas-effect/

http://www.aip.org/history/climate/co2.htm

http://www.bbc.com/news/science-environment-15874560