Oxygen is an overlooked factor in past climate, study suggests

  • 11 Jun 2015, 19:00
  • Robert McSweeney
A view of the Earth and stars from space

Earth from space | Shutterstock

It's well established how carbon dioxide, methane and water vapour affect our climate. But a new study suggests another gas may have played a role in Earth's long climate history - oxygen.

Natural variations in atmospheric oxygen levels could be a missing factor in piecing together Earth's past climate, the researchers say. The findings help explain why climate models tend to simulate temperatures 100m years ago that are lower than scientific evidence suggests.

Oxygen levels

Today, oxygen makes up around 21% of the air we breathe. But that hasn't always been the case. Over the last 500m years, known as the Phanerozoic eon, oxygen levels have been as low as 10% and as high as 35%.

This period has seen the evolution of life as we know it, and scientists know that changes in atmospheric oxygen has been intertwined with how life on Earth has thrived .

Now new research, published today in the journal Science, suggests that oxygen may have had a role in how our climate evolved as well.

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The Carbon Brief Interview: Christiana Figueres

  • 11 Jun 2015, 14:20
  • Leo Hickman
Christiana Figueres

Christiana Figueres | Carbon Brief

Christiana Figueres has been the executive secretary of the  United Nations Framework Convention on Climate Change (UNFCCC) since July 2010 and was reappointed for a second three-year term in July 2013. Before then, she was a member of the Costa Rican negotiating team at the UNFCCC from 1995-2009. In 1995, she founded the non-profit Center for Sustainable Development of the Americas, based in Washington DC.

On defining success at the Paris climate conference this coming December: "If financial support for developing countries to be able to follow that path [to bring their population out of poverty but to do so in a low-carbon, high-resilient way] is made evident, then I think we have success."

The political possibility of limiting the global average temperature rise to 1.5C: "I don't know that it is possible to say right now are we going to end up with 1.5, 1.6, 1.7, 1.8, 1.9C? But it's got to be within that range. There is no doubt that it has to be below 2C."

The legal form of the Paris agreement: "I don't think that the whole agreement is actually going to have the same legal nature [as the Kyoto protocol], but rather there will be several components, key components, that will have different legal nature."

Whether the world could tackle climate change without the UNFCCC: "This has to be done in a way that protects the most vulnerable. That would not occur without the UNFCCC."

How the IPCC can best complement the UNFCCC: "There has been a very clear intent to be more and more guided by science. And you see it in all of the negotiations now that there is much more direct dialogue, in fact, even between the delegates and the scientists, which is a very welcome development."

The usefulness of the IPCC's carbon budgets to the UNFCCC: "I think [they have] brought a sense of realism and a sense of urgency into this discussion."

The challenge and reviewing and aggregating the INDCs [intended nationally determined contributions]: "What we have here is a fruit salad. We have apples, we have pears and we, in fact, even have bananas."

The importance of the Sustainable Development Goals (SDGs) and the UNFCCC: "If we do not address climate change in a timely fashion, we will wipe out all the development gains that have been made in the past 15-20 years. We will wipe that out."

The challenge for the UN of managing these parallel, inter-related processes: "When I first saw it I thought how is this going to be possible, and it is very, very difficult, but...we will remember 2015 as being a very important year in the history of the design of mankind."

On reports that the French will present their own text for a climate deal, if progress at the UNFCCC is slow: "They are not going to come with their own text. This is not a Copenhagen 2.0."

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Climate change could cut growing days of plants and crops by 11%

  • 11 Jun 2015, 10:45
  • Robert McSweeney

Sunrise over meadow | Shutterstock

The number of days each year when conditions are suitable for plants to grow could fall as the climate warms, according to new research.

Researchers in Hawaii found rising temperatures and falling soil moisture could curtail growth of plants and crops across much of the tropics. And if emissions remain unchecked, gains in plant growth at higher latitudes won't make up for these losses.

But other scientists, not involved in the study, tell Carbon Brief the new research may have overestimated the negative impacts of climate change.

Plant growth

Climate change is likely to have both positive and negative impacts on plant growth.

A warmer, more carbon-rich atmosphere could provide better conditions for growth. On the other hand, rising temperatures could make conditions too hot for plant growth. How much water and nutrients plants and crops have access to will also affect how much they can grow.

Scientists have conducted numerous studies into how these factors are likely to play out for different plants and different regions of the world.

The new study, published in open-access journal PLoS Biology, takes a different approach. Rather than estimating how much plants might grow, the researchers focus on how many days each year we'll see conditions favourable for plant growth in the future.

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Irreversible loss of world's ice cover should spur leaders into action, say scientists

  • 09 Jun 2015, 16:25
  • Roz Pidcock
Icebergs in Disko Bay Greenland

Icebergs in Greenland | Shutterstock

We need only look to the world's ice cover to see the urgency with which emissions need to come down, scientists told delegates at this week's climate talks in Bonn, Germany.

At a  press conference today, US and German scientists updated negotiators and journalists with the latest science on the state of Arctic sea ice, the Antarctic continent and thawing permafrost.

New observations gathered since the Intergovernmental Panel on Climate Change (IPCC) report show the cryosphere in serious and irreversible decline, they warned.

Pam Pearson, director of the International Cryosphere Climate Initiative, the network of policy experts and researchers holding the event, told the audience:

"This is not like air pollution or water pollution, where if you clean it up it will go back to the way it was before."

Sea ice in decline

Arctic sea ice has been retreating rapidly in recent years as a result of greenhouse gases building up in the atmosphere, explained Dr Dirk Notz, sea ice expert at the Max Planck Institute in Germany. The biggest losses are happening in summer, he said:

"Over the past 10 years or so, we've roughly seen a 50% loss of Arctic sea ice area. So, the ice in the Arctic is currently retreating very, very rapidly."

In March, Arctic sea ice reached its lowest maximum extent in the satellite record. Last week, the US National Snow and Ice Data Centre confirmed Arctic sea ice extent for May was the third lowest on record.

Antarctic sea ice has been at record high levels in 2015 but this should be viewed  in perspective with what's happening at the other end of the planet, Notz said:

"There is a slight increase, but it's nothing compared to the very, very rapid loss that we've seen in the Arctic."

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No 'slowdown' in global surface temperatures after all, study finds

  • 04 Jun 2015, 19:00
  • Roz Pidcock

A new paper published today says the much-discussed "slowdown" in warming at Earth's surface may not exist after all.

The study, published in the journal Science, says it is likely to be largely a figment of the way temperature records have been pieced together over time.

Scientists from the US National Oceanic and Atmospheric Administration (NOAA) reanalysed temperature records and concluded that surface warming over the past 15 years is higher than reported by the Intergovernmental Panel on Climate Change (IPCC), the UN body set up to assess global warming. Temperatures are rising at least as fast as they were in the second half of the 20th century, say the authors.

Given the interest in the topic, this new finding is likely to generate headlines. But it's probably not the last word on this complex topic, scientists tell Carbon Brief.

To coin a phrase

In its latest report, the IPCC  calculated that the rate of warming from 1998-2012 was 0.05C per decade. Accounting for the uncertainty, this is 30-50% slower than the 0.12C per decade rise over the longer period of 1951-2012. The new paper says:

"The apparent slowdown was termed a 'hiatus', and inspired a suite of physical explanations for its cause."

But the authors say that once you account for improvements to the historical temperature record and a couple more years' of temperature data to take us up to 2014, the pace of warming in the first 15 years of the 21st century hasn't slowed after all.

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Climate change risks biggest change to marine species in three million years

  • 01 Jun 2015, 16:00
  • Dr Grégory Beaugrand & Dr Richard Kirby
Photo of a tropical fish on a coral reef

Tropical reef | Shutterstock

A guest post by Dr Grégory Beaugrand, researcher at the University of Lille Laboratory of Oceanography and Geoscience, and Dr Richard Kirby, research fellow at the Marine Biological Association of the UK.

Humans rely heavily on the world's oceans. About 70% of the world population lives within 60km of the shoreline, and we catch around 80 million tonnes of fish every year. In our new study, we investigate how warming oceans could affect the spread of marine species.

And the results suggest warming over 2C would have a bigger impact on marine biodiversity than we've seen in the last three million years.

Marine biodiversity

We know very little about the many and varied species swimming around in our oceans. Scientists estimate there are around two million different species globally, but so far we have only identified around a tenth of them. This lack of knowledge makes it difficult to predict how climate change could affect marine ecosystems.

But it remains an important challenge.

Until now, attempts to understand the implications of climate change on marine biodiversity have either projected results based on a few key species, or used statistical models to predict the distribution of a species based on different environmental factors.

Both methods are limited by our knowledge of how species are distributed across our oceans. In our study, published today in Nature Climate Change, we take a different approach - using ocean temperatures.

Theoretical species

We use a novel approach based upon the theory that the way biodiversity is distributed in the ocean is based on the temperatures that different species can tolerate and thrive in.

In our ecological model, we created tens of thousands theoretical species. We gave each species a unique response to ocean temperature and allowed them to colonise the world's oceans, wherever they found the temperatures were suitable for them.

To make sure our pseudo-global aquarium was realistic, we checked it against observed data for real species, including types of plankton, crustaceans and fish.

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Warming oceans could mean typhoons are 14% stronger by 2100, study says

  • 29 May 2015, 19:00
  • Robert McSweeney
International Space Station Image of Haiyan

Typhoon Haiyan | Flickr

On 7 November 2013, one of the strongest typhoons in human history hit the Philippines. With gusts up to 171 miles per hour (mph), Typhoon Haiyan tore through the many thousands of islands, killing over 6,200 people and affecting 14 million more.

Every year, these giant storms cause damage and destruction across southeast Asia. Now, a new study suggests that even under a moderate temperature rise, warming oceans could fuel more intense typhoons in the future.

Peak wind speeds

Large tropical storms, sometimes referred to collectively as tropical cyclones, have different names in different parts of the world. In countries around the North Atlantic such as the UK, for example, we call them hurricanes. In the northwest Pacific Ocean, they are known as typhoons.

Typhoon strength is measured by wind speed. Anything over 74 miles per hour (mph) is classified as category one, while only the strongest events with wind speeds over 156 mph reach category five. In the new study, published in Science Advances, researchers assessed how climate change could affect the maximum wind speed of typhoons.

Using typhoon wind speed records for the past 60 years, the researchers looked at how the strength of typhoons has changed. Today, typhoon wind speeds are around 10% stronger than they were in the 1970s.

The destruction caused by a typhoon doesn't just rise in line with wind speed. A 10% rise translates to a 33% increase in destructiveness, the researchers say.

We're also seeing an increasing number of typhoons reaching the highest intensity categories, the study says. 

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The Carbon Brief Interview: Thomas Stocker

  • 28 May 2015, 17:00
  • Roz Pidcock

Thomas Stocker is a professor of climate and environmental physics at the University of Bern. He served as co-chair of working group one for the IPCC's fifth assessment report, coordinating lead author in the third and fourth assessment reports, and is now running to succeed Dr Rajendra Pachauri as IPCC chair.


On new, more realistic climate scenarios: "There are different policy stories that are being developed as we speak."

Big climate questions left to answer: "Science doesn't stop, doesn't stand still."

On 2015 being the hottest year on record: "I think it's extremely daring to - before even half of the year has completed - to come out with that statement."

Attention on the "hiatus" in the last IPCC report: "If there is a topic out there that is debated … I think it's entirely mandatory that we look at it."

Climate sensitivity: "I think climate sensitivity lies somewhere between 2.5 and 3C."

Climate targets: "It will only be a few years [before] the 2C target will become as ambitious as what we are now discussing for 1.5C."

Adaptation and mitigation: "There is a very intimate link … The more you mitigate, the less you are required to adapt."

A role for the IPCC in assessing countries' climate pledges: "On an annual basis, year to year, I don't think that's the task of IPCC."

Climate skeptics and the IPCC: "Well, it's in the nature of truth that sometimes you hate it."

Scientists speaking their mind: "As a citizen in this world, I certainly feel the urge to express my personal views."

Social media: "I simply did not have the time."

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New study: 99% of Mount Everest’s glaciers could be gone by 2100

  • 27 May 2015, 08:00
  • Robert McSweeney
Dudh Kosi basin

Dudh Kosi basin | Patrick Wagnon

A region of the Himalayan mountain range, home to the iconic peak of Mount Everest, could be almost completely free of glaciers by the end of the century, a new study shows.

And the findings may illustrate what could happen to glaciers across eastern and southern parts of the Himalayas, the lead author tells Carbon Brief.

Mount Everest

The Dudh Koshi river basin sits in central Nepal. It's home to some of the world's tallest mountains, including Mount Everest itself, and is one of the most popular climbing and tourist destinations in Nepal.

Around 410 square kilometers of the area is covered in glaciers, huge rivers of ice formed from snow compacted over many years. In this part of Nepal, these are monsoon-type glaciers, which both lose ice through melting and gain it through snowfall during the summer monsoon season.

In a new study, published in  The Cryosphere, researchers use past measurements of the glaciers to develop a model to analyse how they have changed and could change in the future as global temperatures rise.

The graph below shows the model simulations of changes in glacier ice in the basin. Between 1961 and 2007, the volume of ice has decreased by around 16%, while the area covered by glaciers has decreased by 20%.

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Climate change could bring new hay fever misery to the UK

  • 25 May 2015, 16:00
  • Robert McSweeney
Common ragweed

Common ragweed | Nature Bureau

With spring in full swing, there's much to enjoy about sunny days and warmer temperatures. But this time of year also brings the hay fever season, when itchy eyes and sneezing beset around  18 million people in the UK.

Now a new study suggests a warming climate means worse may be on the way. The culprit is the common ragweed, an invasive species that's expanding across Europe with unpleasant consequences for hay fever sufferers.

What is ragweed?

Common ragweed is a green, leafy plant that is native to North America but has taken root in Europe, Australia, East Asia and South America since the end of the 19th century.

Ragweed typically grows around farmland and construction sites, and along riverbanks and railway embankments. It flowers through the summer and into the autumn and produces large amounts of pollen, which can be carried by the wind from one country to another.

The UK is currently a bit too cold for the plant to flourish. And while ragweed pollen is blown over from Europe, it's rarely in high enough quantities to cause hay fever symptoms.

But that could be set to change. New research, published in Nature Climate Change, estimates the amount of ragweed pollen in the air across Europe will be four times higher by 2050. And it could even be as much as 12 times higher, the study shows.

This means a lot more ragweed pollen reaching the UK, the researchers say.

The study is part of a Europe-wide project on how changes in climate, land use and air pollution will affect the spread of pollen and its impact on human health.

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