Climate change: the evidence

In recent years the temperatures we’ve experienced are by far the highest since temperature records began. In fact, all of the 10 warmest years have occurred since 1990, including every year since 1995.

Scientists have also been able to look back further into our past to estimate temperature variations using indirect measurements such as tree rings, coral layering and glacial ice cores. This evidence clearly shows that recent warming is unlike anything seen in thousands of years.

This graph combines together the indirect measurements (such as ice cores) and direct temperature measurements over the last 1000 years. The recent increase is totally unprecedented.

It then shows a number of different projected temperature changes over the period to 2100, based on our understanding of the greenhouse effect, and estimates of how our emissions of Carbon Dioxide will increase in the coming years as our energy use and populations increase.

Source: Intergovernmental Panel on Climate Change (IPCC) – 2001 Report

But is it really our fault?

Yes, unfortunately the evidence is overwhelming.

It’s true that the temperature of the earth has varied dramatically over the millions of years of its history. However, the recent changes have been so fast that they cannot be explained by the normal natural climate processes.

The leading scientists from around the world have built powerful computer models to simulate the impact of man’s activities on the climate. They have shown that the only way that the recent temperature changes can be explained is by taking into account the levels of Carbon Dioxide and other greenhouse gases emitted directly by man’s activities.

This graph compares a computer model simulating the natural climate effects over the last 150 years against the actual observed temperature increases.

It’s clear that natural effects alone are not sufficient to explain the warming we’ve experienced.

This second graph adjusts the computer model to also simulate the impact of man’s greenhouse gas emissions over the same period.
This shows conclusively that it’s only when you add in man’s impact that you can explain the recent temperature increases.

Source: Intergovernmental Panel on Climate Change (IPCC) – 2001 Report

Seeing is believing

Perhaps the most clear and prominent evidence of climate change is the retreat of mountain glaciers, which has been a worldwide phenomenon.

The two pictures below of an alpine glacier in Kärtnen (Austria) illustrate just how dramatic the change in temperature has been.

Glacier Size in 1900
Source: Munich Society for Environmental Research

Evidence is also clear around both poles. In the Arctic the ice cap is shrinking, whilst in Antarctica the ice shelf is melting and there have been rapid rises in local temperatures around the peninsula.