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A new study attributes the retreat of glaciers in the Andes to rising global temperatures. Glaciers in the region are losing ice faster than at any time in the last 300 years. Some smaller glaciers are at risk of disappearing altogether, the research concludes. So are glaciers reaching a critical situation? We look at the new research in context.

The Andes in South America are home to 99 per cent of the world's tropical glaciers - those located high up in mountain ranges around the equator. The new study, published today in journal The Cryosphere, monitored about half of all Andean glaciers across Colombia, Bolivia, Peru and Ecuador to see how the volume of ice they contain has changed since the 1970s.

The scientists used field measurments and satellite data to survey an area of almost a thousand square kilometres, making the new study the most comprehensive review of Andean glaciers so far.

Andean meltdown

The research showed although there have been some "sporadic gains" in ice mass for several glaciers in the survey region, overall they are in decline. On average, the glaciers lost about 30 to 50 per cent of their mass since the 1970s, and the rate they are shrinking is accelerating. According to the study, the rate of melting is now unprecedented in the last 300 years.

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Mayor of London Boris Johnson bemused the world in the run up to the Olympics with a patriotic  speech about table tennis's purported ancestor 'whiff-whaff', an ancient game built around the idea of a good back and forth. 

Johnson's conception of climate science also seems to be based around the idea of a good back and forth - between scientists and skeptics. He gave his latest thoughts on the subject for   Telegraph readers today, as from his window in snowy Islington, he muses on the subject of snowy winters. He turns to the theories of climate skeptic meteorologist, Piers Corbyn, who believes that far from warming, the globe might be heading for a "mini ice age".

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Jay Galvin

Last week provided a timely reminder that global temperatures - although important - are by no means the only sign of climate change. A preliminary report released by the World Glacier Monitoring Service shows a swathe of the planet's glaciers are in retreat.

The new analysis, which provides the latest data for 2011, shows glaciers around the world are losing ice. But it also shows plenty of natural variation between different regions and from year to year.

This year's report from the World Glacier Monitoring Service (WGMS) - just released - examined data from a selection of 108 glaciers including the Alps and the Andes, as well as others across North and South America, Europe and Asia.

As well as looking at year to year changes, the WGMS also monitors how glaciers are responding to  rising global temperatures, which means looking at how glaciers change over successive decades.

Global decline

Let's start by looking at what this year's data show. Scientists at WGMS have been measuring 37 of the 108 glaciers continuously since about 1980. These 'reference glaciers' have the longest complete data record.

The scientists found that, on average, each reference glacier lost a volume of ice equivalent to one metre of thickness during 2011. This brings the total amount of ice lost up to more than 15 metres since 1980, with the rate of loss speeding up since about 2000.

The amount lost varied considerably between glaciers. According to the data, the Sarenne glacier in the French Alps lost the equivalent of four metres of thickness during 2011 - the biggest loss from a single glacier.

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Heat

This week scientists from NASA released analysis showing that 2012 was the ninth warmest year since 1880. Nine of the ten warmest years have occurred since 2000.

"Scientists emphasize that weather patterns always will cause fluctuations in average temperature from year to year, but the continued increase in greenhouse gas levels in Earth's atmosphere assures a long-term rise in global temperatures," the press release stated.

A new study found that monthly temperature extremes have become more frequent across the world. In Australia, scientists warned against directly attributing the current heat wave to climate change, but said it's clear a warming world increases the likelihood and intensity of heatwaves.

Last year was the hottest on record for the USA, and this week saw the release of a report assessing the impact of climate change on the country. The 1,000 page draft National Climate Assessment starts fairly bluntly:

"Climate change is already affecting the American people... Evidence for climate change abounds, from the top of the atmosphere to the depths of the oceans... The sum total of this evidence tells an unambiguous story: the planet is warming."

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NASA Goddard Institute 

On Tuesday, NASA released its latest annual analysis of global temperatures - which shows 2012 was the ninth warmest year since records began in 1880. But does one year's temperature data tell us anything about climate change? We asked some scientists for their thoughts.

2012 in context

In a report accompanying the data,  Dr James Hansen, chief scientist at NASA Goddard Institute for Space Studies (GISS), says:

"Global surface temperature in 2012 was +0.56°C (1°F) warmer than the 1951-1980 base period average...2012 is nominally the 9th warmest year [since 1880]."

It might be tempting to focus on this fact, but it's not that simple. As Dr Richard Allan, climate scientist at the University of Reading told Carbon Brief, looking at temperature data for a single year is not very informative.

"The fact that 2012 was the ninth warmest year on record does not tell us much about climate change. Global temperatures fluctuate naturally from year to year by as much as half a degree Celsius."

Or as  Dr Gavin Schmidt, climate scientist at NASA GISS told us:

"That 2012 is fifth, ninth, or twenty-seventh is not really the point. Instead, it is the fact that the long term trends and the decade-on-decade differences are all up (as has been predicted for decades)."

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Monday's Daily Express provided a helpful run-through of some rather tired climate skeptic memes, courtesy of columnist Leo McKinstry. It didn't deviate from the Express's editorial line on climate change, which appears to be broadly supportive of arguments that a)  It isn't happening and b) It's not our fault anyway.

Unfortunately, we're guessing the picture of 'climate science' presented in the article isn't one scientists would recognise. Here are five ways  the article gets it wrong:

1. Global warming is still happening

McKinstry begins with the  familiar skeptic argument that recent global temperature data show global warming "is not happening". He says:

"According to recent studies from the Meteorological Office there has been no significant increase at all in the world's temperatures since 1997"

Adding:

"Met Office admits that there will not be any global warming over the next four years."

This argument has done the rounds recently, following the release of the Met Office's analysis of   global temperature data, and its   latest decadal forecast projecting temperatures up to 2017.

We've gone over the detail of these arguments extensively in the past few days - see  here and  here if you want more. But seeing as this is all referencing Met Office data, what is the considered view of the Met Office on this issue? As it said  last week:

"Small year to year fluctuations such as those that we are seeing in the shorter term five year predictions are expected due to natural variability in the climate system, and have no sustained impact on the long term warming".

This reiterates the Met Office's expectation that global temperatures will  continue to rise in the 21st century. In response to a  specific claim last week that the Met Office had "admitted there is no evidence that global warming is happening", The Met Office clarified it has "not said this at any point."

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I'll begin with two questions:

What proportion of Americans say there is solid evidence that the earth is warming?
Is it: a) one quarter; b) one third; c) a half; or d) two thirds.

What has happened to that figure over the last four years?
Has it: a) fallen every year; b) stayed about the same; c) risen every year.

Judging by most conversations I have and the coverage of public views about climate change, most people would guess the answer is low and falling.

But here's the answer, taken from the  Pew Research Center's annual polls: two thirds and rising.

Agreement in the US that the earth is warming is now higher than it's been at any time since 2008. The research was conducted before Hurricane Sandy, so is probably higher now.
Sure, still only about half say it's because of human activities - though that has also increased by a quarter over the last three years.

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The Met Office has today published an explanation of how it forecasts decadal temperature trends following news that it has revised downwards its decadal prediction of likely global temperature rise up to 2017. These measurements focus on short-term fluctuations in the climate system, not long-term climate trends. So why has a scientifically significant - though, in the scheme of things, relatively minor - adjustment to an experimental forecast ended up being heralded in the Daily Mail as evidence the Met Office has admitted climate change isn't happening?

In the  Daily Mail, skeptic blogger James Delingpole claims that the Met Office "quietly readjusted its temperature projections" on Christmas Eve, conceding  that "'global warming' isn't happening" after it produced a new decadal forecast. The Met Office has been responding to claims that warming has stopped all week, explaining that the forecast in question only relates to short term fluctuations in the climate - and certainly doesn't mean warming has stopped. We take a look at what decadal forecasts are, and what they really mean.

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Met Office temperature predictions - hot or not?

Over the festive break the Met Office released new analysis revising downwards a prediction for how much temperatures are likely to rise over the next five years or so. This prompted a rash of stories this week claiming that global warming is at a " standstill".

Temperatures are rising slower than in previous decades because, scientists say, natural fluctuations in the climate system are temporarily masking warming caused by humans. But over a longer timescale - like more than a few years - the upward trend in global temperatures is going to continue, barring a cut in greenhouse gas emissions. We explain more in a blogpost.

This didn't stop some parts of the media from arguing that that climate change isn't happening. The Guardian rounded up responses from the media and from climate scientists - one of whom described claims that temperatures aren't rising as "just daft".

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This week, Australia is experiencing an unprecedented heatwave, sparking wildfires that have ravaged the country. We take a look at how far the heatwave and its consequences can be linked to climate change.

On Monday, temperatures in Australia reached a national average of 40.33 degrees Celsius -  beating the previous record set in 1972.

And it's not over yet - the temperatures forecast for next week are so high, officials have  added the colour purple  to forecast maps to reflect how extreme the predicted temperatures are.

Now on its seventh day of exceptionally high temperatures, Australia is officially experiencing a heatwave. The  World Meteorological Organisation define this as at least five days of temperatures above the long term average.

With seventy percent of the continent affected, David Jones from the Bureau of Meteorology's explained to  Australian media:

''The current heatwave - in terms of its duration, its intensity and its extent - is now unprecedented in our records.''

What's causing the heatwave - is it climate change?

Just like the  rest of the world, the average temperature in Australia has risen in the last century due to  human activity. According to a  recent study  by the Australian Bureau of Meteorology, the average temperature across the continent has gone up by 0.9 degrees since 1910.

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