The Science of Climate Change

(Pour la version française, veuillez cliquer ici.)

“No challenge poses a greater threat to future generations than climate change” (Barack Obama)

What is Climate Change?

The UK Met Office defines climate change as a large-scale long-term shift in the planet’s weather patterns or average temperatures.   In its long history the Earth has had many changes in its climate but it has been relatively stable since the last big change ended about 11,000 years ago.  However, over the last hundred years or so there has been an unusually rapid increase in the Earth’s average surface temperature.  This is called global warming and is principally due to the particular gases (called greenhouse gases) released as people burn fossil fuels like oil, gas and coal. Here is an article about fossil fuel divestment.  Greenhouse gases are also produced on a large scale from deforestation and industrial-style agriculture.  The most common gases you will hear about are carbon dioxide and methane although there are others. Almost all scientists now agree that this global warming is manmade.

The scientific evidence shows clearly that global climate change is caused by humans. Here is an article explaining how we know that humans caused Climate Change.

Or this article written by the EU on the causes of Climate Change shows that “Humans are increasingly influencing the climate and the earth’s temperature by burning fossil fuels, cutting down forests and farming livestock.”

How do we now know it is manmade and not created by volcanoes or sunspots or other natural occurrences?  It is complicated, but scientists can calculate how much warming there should be from naturally produced greenhouse gases. This is not enough to produce the present effect.  Essentially, carbon dioxide in the atmosphere produced from the burning of fossil fuels has a special chemical footprint that can be measured.

What are greenhouse gases?

Greenhouse gases remain in the atmosphere for a very long time and act like a blanket that keeps heat from escaping from the earth.  A certain level of these gases is a good thing and has allowed Earth to remain at a temperature where life is possible.  However, the planet is now warming at a level and at a rate that adversely affects not just human beings but all life.

Here greenhouse gases are explained by NASA.

Not only is the Earth getting hotter and drier in some areas, and wetter in others, but our weather is becoming much more unpredictable and sometimes just downright dangerous. We have had huge increases in super-storms, flooding, droughts and forest fires.  This can be seen in the number of weather-related insurance claims. These have increased considerably over the last 30 years or so to about $138 billion globally in 2017. More recent years are likely to have been more costly.

How do we know the planet is warming?

 To ordinary people it is clear that something strange is going on.  The primroses are blooming in December and swallows are arriving earlier each year. Birds are nesting and producing young when the insects have not yet hatched to feed them. Farmers are complaining of unpredictable planting and harvesting times and weather forecasters tell us each month that it is the hottest on record.  But how do the scientists know the earth is getting warmer?

1. There are temperature measuring stations all over the world with records going back many years
2. Glacier are melting faster all the time
3. The sea-level is rising
4. There is considerable loss of biodiversity
5. Ocean temperatures are increasing
6. There is increased humidity in the atmosphere
7. The Arctic and Antarctic icecaps are melting
8. The Arctic will become ice-free throughout the year

These changes are occurring faster than we thought they would and are likely to have devastating effects on future generations. Thus, it is vital that we speed up our reactions to climate change.  Greenhouse gases stay in the atmosphere a long time and we are not yet feeling the full effect of gases already up there.

What are the effects of Climate Change?

 These are only some of the effects:

• Our weather is becoming much more unpredictable and difficult
• Ocean temperatures are increasing with negative effects such as corals dying on a huge scale. Coral reefs act as nurseries for our fish stocks so they will also diminish.
• Sea levels are rising and will flood many major cities sooner or later
• Warmer weather will affect the productivity of food crops
• Desertification through drought is reducing land area for food production
• Melting glaciers, for example in the Andes and the Himalayas, threaten the water supplies of millions of people
• The decrease in biodiversity, according to WWF means that “millions of people face a future where food supplies are more vulnerable to pests and disease and where fresh water is irregular or in short supply”

We CAN slow this down and make sensible adaptions if we can persuade our politicians to take more drastic actions NOW.

For information on the urgency of tackling Climate Change try “Why Are We Waiting” by Nicholas Stern who originally wrote the Stern Report on the economics of Climate Change.

Or for a rather more scientific description read “Breaking Boundaries” by Johan Rockström and Owen Gaffney.