Climate Change – The Facts

I have been asked by a couple of people to produce a simple climate change factsheet, and it might be worth bookmarking for future use.

I have kept it simple, with no graphs or references. As those familiar with this blog, everything below has been fully covered a number of times. Anybody who needs more explanation on a particular item only needs to ask.

Any comments are welcome.

CLIMATE CHANGE – THE FACTS 

1) Global Temperatures

It is generally reckoned that global temperatures have risen by about 1C since the late 19thC. This, however, is only a guesstimate at best, as most of the world had very little climate data in those days

According to satellite data, temperatures have not increased since 1998.

2) Little Ice Age

Any discussion of temperature rise since the 19thC needs to be put in the context of the Little Ice Age, which lasted around 500 years and ended in the late 19thC.

Scientists believe that this was the coldest period since the end of the Ice Age, and evidence shows that it was a worldwide event, although timings were not always the same.

The Little Ice Age succeeded the Medieval Warm Period, which again appears to have been a global event, during which temperatures were at similar levels as today.

3) Glaciers

Melting of glaciers is often held up as “proof” of global warming. But in fact, they began retreating in the 19thC, long before current “man-made” global warming. There is particularly strong evidence of this fact, as Alaskan and Alpine glaciers were already being closely surveyed as early as the late 18thC.

As the glaciers in Alaska retreat, they are uncovering the remains of ancient forests, which have been carbon-dated back to the Middle Ages, indicating the glaciers were much smaller then. Exactly the same has occurred in Patagonia.

Evidence from around the world, including South America and New Zealand, confirms that there was a massive growth in the size of glaciers between the Middle Ages and the end of the Little Ice Age.

Glaciologists have established that many glaciers in both Greenland and Iceland reached their post ice age maxima during the 18th and 19thC.

4) Arctic

We hear a lot about temperatures rising in the Arctic, and icecaps melting.

In fact, temperatures around the Arctic show little difference now to what they were in the 1930s and 40s. Subsequently, they fell sharply in the 1970s and 80s, before rising again. This cycle appears to be connected to multi-decadal ocean cycles

Arctic sea ice retreated as a result until 2007, since when it has remained stable. Satellite data for sea ice extent is only available since 1979, in the middle of the colder interlude, and therefore cannot provide reliable long term trends.

The ice cap in Greenland has also been slowly melting, but the amounts involved are extremely tiny in relation to the total ice mass. Again, long term temperature records in Greenland show that temperatures were as high in the 1930s and 40s.

On a longer timescale, scientists also know that temperatures throughout the Arctic have been much higher than now for the last 10000 years.

5) Antarctica

Sea ice around Antarctica has been stable since 1979 if anything increasing slightly.

NASA has established that the Antarctic ice cap has actually been growing since 1992 because snowfall has more than offset thinning glaciers.

6) Sea levels

Since the ending of the Little Ice Age in the late 19thC, global sea levels have risen by about 8 inches. Sea levels around the UK give a similar result, after allowing for vertical land movement. (Most of England has been sinking since the ice age).

The recent rate of rising has been slightly higher, about 10 inches per century, sea levels were also rising at a similar rate in the mid 20thC.

7) Extreme weather

There is no persuasive evidence that extreme weather is getting either more common or severe:

a) According to the Intergovernmental Panel on Climate Change (IPCC), there is no evidence of any long term increase in hurricane activity.

b) US data confirms that tornado activity has declined since the 1970s when proper records began. Notably, data also shows that there are now fewer of the most violent tornadoes.

c) The IPCC also report little evidence that flooding is getting worse.

d) Equally, they find little proof that droughts are becoming worse globally, though there inevitably regional differences.

e) Wildfires, contrary to popular myth, are claiming many fewer acres than they did in the past.

One of the biggest sources for the myth of extreme weather is 24/7 media coverage, which now brings events into our homes which would have gone unreported not long ago.

In the UK, long term data also provides no evidence of an increase in extreme weather, such as storms, floods, and droughts.

8) UK climate trends

According to official Met Office data, UK temperatures stopped rising about fifteen years ago. The summer of 1976 remains the hottest on record, as well as having the most intense heatwaves.

Furthermore, there is no evidence of any significant changes in rainfall trends, other than in Scotland which has experienced higher rainfall in recent decades.

9) Climate projections

All of the scary forecasts concerning temperatures, sea-level rise, etc., are based on computer modeling of the climate. However, these models have consistently grossly overestimated the small rise in temperatures actually experienced.

10) UK Climate Change Act

The 2008 Climate Change Act committed the UK to reduce emissions of carbon dioxide and other greenhouse gases by 80% from 1990 levels by 2050.

Since the Act was passed, the UK’s CO2 emissions have reduced by 183 Mt, representing 31% of 1990 levels. However, this has come at a great cost.

This year, subsidies for renewable energy are forecast to hit £12.2bn, equivalent to about £450 per household.

This year, however, Parliament approved changes to the Act which alter the target from an 80% cut to 100%. Official estimates put the cost of this at £50bn a year by 2050, some £1800 per household.

11) Global emissions

While UK emissions have dropped by 183 Mt since 2008, global emissions have increased by 3389 Mt. UK emissions are now only a tiny 1% of global ones.

Despite the hype, the Paris Climate Agreement, signed in 2015, won’t do anything to reduce emissions, as most countries plan to carry on increasing them until at least 2030. Notably, these include China and India, which account for 35% of the world’s carbon dioxide.

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