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Simple Data Science of Global Warming


You don't have to be a climatologist to empirically confirm global warming. It is enough to have a computer, a reliable data set of historical temperatures, and software like R to do simple calculations.



By Antonio Sánchez Chinchón.

Global warming is real. Winters come later and milder and summers come sooner and hotter. Many people and many species are being affected by the climate change. Scientists have made it clear that human activity is the main cause of this change and warn that damages caused so far (rise of sea levels, acidification of the oceans, melting of glaciers) will remain for centuries if governments don't take drastic measures to counteract global warming.

The Intergovernmental Panel on Climate Change (IPCC) is the leading international body for the assessment of climate change. It was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) in 1988 to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts. These are some of their last forecasts (1):

  • Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems. Limiting climate change would require substantial and sustained reductions in greenhouse gas emissions which, together with adaptation, can limit climate change risks.

  • Cumulative emissions of CO2 largely determine global mean surface warming by the late 21st century and beyond. Projections of greenhouse gas emissions vary over a wide range, depending on both socio-economic development and climate policy.

  • Surface temperature is projected to rise over the 21st century under all assessed emission scenarios. It is very likely that heat waves will occur more often and last longer, and that extreme precipitation events will become more intense and frequent in many regions. The ocean will continue to warm and acidify, and global mean sea level to rise.

  • Each of the last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850. The period from 1983 to 2012 was likely the warmest 30-year period of the last 1400 years in the Northern Hemisphere, where such assessment is possible (medium confidence). The globally averaged combined land and ocean surface temperature data as calculated by a linear trend, show a warming of 0.85 °C over the period 1880 to 2012, when multiple independently produced datasets exists.

  • Anthropogenic greenhouse gas emissions have increased since the pre-industrial era, driven largely by economic and population growth, and are now higher than ever. This has led to atmospheric concentrations of carbon dioxide, methane and nitrous oxide that are unprecedented in at least the last 800,000 years. Their effects, together with those of other anthropogenic drivers, have been detected throughout the climate system and are extremely likely to have been the dominant cause of the observed warming since the mid-20th century.

Is not necessary being a climatologist to confirm empirically global warming. It is enough to have a computer, a reliable data set of historical temperatures, and software like R to do some simple calculations. The European Climate Assessment & Dataset Project (ECA) site provides information on changes in weather and climate extremes, as well as the daily dataset needed to monitor and analyze these extremes. The ECA dataset contains series of daily observations at more than 2.500 meteorological stations throughout Europe. There are observations from the late 18th century to the present, although not all stations have records for the complete period.

It is easy to obtain a rough idea of the evolution of global temperature measuring the linear trend of the average temperature recorded by each station. This is the distribution of the meteorological stations according to this historical trend:

Evolution of Temperatures in Europe and Mediterranean

The distribution is significantly centered above zero: here we have the effect of global warming. Since ECA dataset provides geographical coordinates for every station, is also easy to locate in a map those with the highest trends. To do it I use the amazing googleVis R package:

Climate Data Hotpoints
Click on the image above to open interactive data visualization

One of these stations is located in In Amenas (Algeria). These are the temperatures registered by this station from 1958 to 1998:

Temperatures in Amenas, Algeria 1958 to 1998

The rise, although very gradual, is palpable.

Some days ago I read an interview with Bjorn Stevens, director at the Max-Planck-Institute for Meteorology where he leads the Atmosphere in the Earth System Department. He says, the big challenge is to require our politicians to learn from the best available knowledge: there is understandable information available to whoever wants to know.

Let’s hope they do.

(1) IPCC Climate Change 2014 Synthesis Report

Here is the R code for this post.

Bio: Antonio Sánchez Chinchón is mathematician and works as data scientist at Telefónica. He is the creator of Ripples, an unclassifiable blog of mathematical experiments and R programming. You can follow him in @aschinchon

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