Solar Activity and the so-called “Little Ice Age”

  • 01 Nov 2013, 12:55
  • Professor Mike Lockwood

I'm a professor of space environment physics and a director of research at the University of Reading in the UK. My particular topic of research is the sun, how it changes over time and how those changes affect the space environment, the weather and the climate on Earth.

In the last few years, my work has focused on how temperatures in the northern hemisphere have responded to periods in history when the sun has been very quiet. The "activity" of the sun's magnetic field is related to the number of sunspots that appear on its surface.

The sun's activity rises and falls on an approximately 11-year cycle, but also varies on century-long timescales. It's this research I talked to BBC weatherman Paul Hudson about in an  interview for the BBC's Inside Out programme.

Unfortunately, I now find myself in the position of being  cited as predicting that the current rapid decline in solar activity will plunge the world into a "Little Ice Age".

This is very disappointing as it is not at all supported by the science. 

Weather and climate are inherently complicated - and uncovering and attributing past changes is very difficult. So it's worth being clear about the state of the science, as well as some of the myths, misconceptions and misnomers that abound in this area.

The "Little Ice Age" wasn't really an ice age

Let us start with the term "Little Ice Age". I personally dislike it and avoid using it, as I don't think it was an ice age of any shape or form.  

There is some evidence for a prolonged period of somewhat lower global mean temperatures beginning in around 1400 -1500 (estimates vary) and ending sometime between 1700 and 1800. 

This has been termed the " Little Ice Age" and is often wrongly linked with the Maunder minimum in solar activity, a period between about 1650 and 1700 when almost no sunspots were seen.

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Eight years' worth of current emissions halves the chances of staying below two degrees warming

  • 23 Oct 2013, 14:15
  • Roz Pidcock

Limiting global warming to two degrees above pre-industrial levels will require "substantial and sustained" cuts in greenhouse gas emissions, the Intergovernmental Panel on Climate Change (IPCC) said in its latest  report.

It went a step further by proposing a "carbon budget" - a first for the IPCC reports. This is a total amount of carbon we can put into the atmosphere while still having a good chance of staying below the critical two degree threshold.

How scientists work out the budget is quite complicated - we have written a more detailed briefing  here. But here are the most important bits.

Two thirds of the budget is already spent

According to the IPCC's calculations, 800 billion tonnes is the maximum amount of carbon we can release through carbon dioxide emissions to still have a 66 per cent chance of limiting warming to two degrees - a probability the IPCC terms "likely".

This budget allows for some additional warming to come from emissions other than carbon dioxide, including methane, CFCs, ozone, nitrous oxide and black carbon.

Carbon dioxide emissions over the industrial era have put about 531 billion tonnes of carbon into the atmosphere - which means we've already 'spent' about two thirds of the budget.

If emissions were to continue at current levels, the remaining budget - about 270 billion tonnes - would be exhausted in about 25 years.

To stay within budget, any fossil fuels that would put us over budget would have to be left in the ground - or the emissions  captured before or after entering the atmosphere.

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Carbon briefing: Making sense of the IPCC’s new carbon budget

  • 23 Oct 2013, 10:00
  • Roz Pidcock

Last month, the Intergovernmental Panel on Climate Change (IPCC) released its fifth 'assessment report', which provide a detailed look at the science of climate change.

The latest report  is the first to include an assessment of a "carbon budget" - a finite amount of carbon that can be burnt before it becomes unlikely we can avoid more than two degrees of global warming.

So how big is the carbon budget, how was it calculated, and how does it help us understand the challenge of limiting climate change?

A budget for two degrees

In 1992, the United Nations Framework Convention on Climate Change (UNFCCC) decided the objective of global climate policy should be to stabilise humans' influence with the climate below the level at which it can be considered "dangerous".

The most widely accepted threshold is two degrees of warming relative to pre-industrial times - this is the limit recommended by the UK's  Committee on Climate Change, for example.

In its new report, the IPCC includes a calculation of how much carbon we can emit and still have a reasonable chance of staying below two degrees.

It calls this amount a carbon budget. The budget is an upper limit on total human emissions, from the beginning of the industrial revolution until the day we stop burning carbon.

To stick to the budget, any fossil fuels that would take us over-budget will either have to be left in the ground, or the emissions  captured before or after entering the atmosphere.

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Scientists react to today’s UN climate report

  • 27 Sep 2013, 17:45
  • Roz Pidcock

Today an international group of hundreds of climate scientists released a report covering how and why the earth's climate is changing, and how it may change in the future.

We wrote a summary of the report's top findings and a simple background for everyone. But how has the report been received by the scientists involved? We asked a few for their reaction.

Scientists are 95 per cent confident that humans are changing the climate

The topline from the new report - and one many media outlets have picked up on - is that scientists can now say with extremely high confidence the world is warming and that humans have been the dominant cause of that warming since the 1950s.

Dr John King from the British Antarctic Survey tells us:

"[T]he message I would want people to take home is increasing certainty that human activity has been having an impact on climate and will continue to do so into the future, that we are now able to make predictions with increased confidence"

King adds a note about how confidence in this message has grown stronger in recent times, saying:

"I think it's interesting to look at this in the context of the whole series of IPCC assessments that have come out. We're now on the fifth one and over time the message that has become stronger and stronger that there is a measurable human impact on climate ...The message hasn't changed, it's just being delivered with greater and greater confidence as the evidence base has accumulated"

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UK media gear up for major climate report

  • 23 Sep 2013, 18:00
  • Roz Pidcock

With a week until the UN's climate body releases its new report on how and why the climate is changing, the media are limbering up in anticipation. Here's a quick look at who saying what.

Although the full report from the Intergovernmental Panel on Climate Change (IPCC) is not yet in the public domain, the draft version of a draft guide for policymakers was  leaked to  journalists a few weeks ago.

Scientists and policymakers are discussing the wording of the summary in Stockholm this week, and a final version is due for release on Friday morning.

"Stark warning"

The report looks set to increase the certainty with which scientists can point to human influence on climate change - and this forms the backbone of some of the coverage.

A two-page spread in yesterday's  Observer carries the headline 'IPCC issues stark warning over global warming'. The piece lays out what appears to be the top finding from the new report: scientists are surer now than ever human activity is the biggest source of warming since the 1950s.

With the help of a handy 30-second explainer on the IPCC, the BBC reports this morning:

"Scientists will underline, with greater certainty than ever, the role of human activities in rising temperatures."

While a lot of the discussions about the new report are likely to concentrate on temperatures at earth's surface, the evidence for warming is stacking up in other areas too. Ice sheets are dwindling, the oceans are warming and sea levels are rising, reported yesterday's  Independent:

"[D]raft pages show that in addition to temperature rises, changes are being observed throughout the climate system."

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Poll appears to show growth in climate skepticism - but what kind is it?

  • 19 Sep 2013, 16:20
  • Mat Hope

Credit: The Italian Voice

Humans are complicated beings. Nowhere is this more obvious than when examining polling results, and sometimes pollsters' questions don't bring out the most coherent answers.

This morning, the  Times declared that the UK public is becoming increasingly climate skeptic. So what insights does the polling offer?

Climate skepticism quadrupling

The Times reports the results of a new poll from the  UK Energy Research Centre (UKERC), and suggests the proportion of people in the UK who don't think the world's climate is changing has more than quadrupled since 2005.

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‘Carbon pollution’: What’s the use of a new term in the climate debate?

  • 04 Sep 2013, 15:00
  • Ros Donald

Carbon pollution - it sounds made up, and it is. We examine the birth of the new term and whether it could help create a more accurate climate debate.

Communicators have long been interested in which terms in the climate debate have the greatest resonance. Perhaps the best-explored is whether it's more effective to refer to  'global warming' or to 'climate change' - which some US studies have shown to affect how concerned people feel about the climate.  

In June, one of the world's most quoted people threw a new term into the mix: 'carbon pollution'. In a  speech, US president Barack Obama addressed the scientific basis for climate change, saying: "... year after year, the levels of carbon pollution in our atmosphere have increased dramatically". He repeated the term another 29 times. 

US government departments such as the Environmental Protection Agency and NGOs like the  Center for American Progress  are also using  the term, which now appears on their websites as of this year. 

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Taking Earth's temperature: Three Met Office reports examine the warming pause, climate sensitivity and taking a broad view of climate change

  • 25 Jul 2013, 12:45
  • Roz Pidcock

Much of the debate around climate change taking place in the media, online and in the world of campaigning focuses on the part of the planet where human live - the surface. We are warned about climate change in terms of temperature rise - two degrees is 'dangerous' - and when temperatures don't rise steadily, some claim that "global warming has stopped".

Last week  saw a piece on the BBC's Sunday Politics which focused in a graph  showing surface temperature from 1980 to argue global warming had "plateaued", suggesting that climate scientists were at a loss to predict or explain it.  

With impeccable timing, the Met Office has just released  three useful reports on this very topic, which explore some reasons why looking only at surface temperatures might mean you're missing the broad picture.

Taking earth's temperature

The  three reports, published this week, have a lot of interesting detail and are worth a read in full.

The  first looks at what different measurements of the earth's system  can tell us about climate change. The  second looks at what's causing surface warming to slow, and the  third looks at whether the slowdown affects projections of substantial warming by the end of the century.

On surface temperatures the Met Office says:

"Global mean surface temperatures rose rapidly from the 1970s, but have been relatively flat over the most recent 15 years to 2013."

A broader look at climate change considers other indicators of how the climate is changing, the reports say. One pretty clear indicator is Arctic sea ice. 



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Communicating the risks and uncertainties of climate change at the science and technology committee

  • 05 Jul 2013, 12:14
  • Marion Ferrat

Last week the House of Commons Science and Technology Select Committee met at London's Science Museum to  take evidence from experts on communicating the risks and uncertainties linked to climate change. Marion Ferrat, climate scientist at Imperial College London, offers her take on the session.

The question at the centre of the Science and Technology committee's investigation is that of the link between scientists, government, the media and the public: What are the respective roles of these groups, and how can science communication be improved to create dialogues about climate science?

At the session held at the Science Museum a range of climate scientists and experts in science communication gave evidence, and the discussion was wide ranging.

What is the role of a scientist?

The panel suggested four main roles for scientists - to undertake research, to identify issues of relevance and work at solving them, to explain their work, and to assist in decision-making by communicating their results.

Professor John Pethica, Vice-President of the Royal Society, stressed that it was the duty of scientists not just to do the science, but also to participate in the discussion. The witnesses generally agreed that despite lots of progress in scientists talking about their work, there needs to be better training in communication for scientists.

Researchers are trained to communicate their results to other scientists at conferences and scientific publications, but often do not know how to deal with the emotional response involved with communicating results that have a direct impact on people's lives, it was suggested.


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Trust and balance: Why it’s so hard to communicate climate change

  • 19 Jun 2013, 14:30
  • Mat Hope

Selena Wilke

Science, policy, politics and  post-Copenhagen trauma have become intertwined in public understanding of climate change. That can make communicating the core issues very difficult.

The House of Commons Science and Technology Committee this morning asked three experts how to better engage the public on climate change. It made for a fascinating session, which captured the difficulties of communicating climate change - and threw up more questions than it answered.

Knowing who to trust

One of the most difficult issues facing anyone interested in climate change is knowing where to go for credible information. University of Glasgow sociologist Dr Catherine Happer, told the committee it is increasingly difficult for the public to choose who to trust in the "digital environment".

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