Selected category: Basic Science of Global Warming

Six Climate Tipping Points: How Worried Should We Be?

One of the biggest fears about climate change is that it may be triggering events that would dramatically alter Earth as we know it.

Known to scientists as “tipping events,” they could contribute to mass extinction of species, dramatic sea level rise, extensive droughts and the transformation of forests into vast grasslands – among other upheavals our stressed world can ill afford.

Here are the top six climate events scientists worry about today.

1. The Arctic sea ice melts

The melting of the Arctic summer ice is considered to be the single greatest threat, and some scientists think we’ve already passed the tipping point.

As sea ice melts and the Arctic warms, dark ocean water is exposed that absorbs more sunlight, thus reinforcing the warming. The transition to an ice-free Arctic summer can occur rapidly – within decades – and this has geopolitical implications, in addition to a whole ecosystem being disrupted.

Photo: Smudge 900)

2. Greenland becomes ice-free

The warming of the Arctic may also render Greenland largely ice-free. While Greenland’s ice loss will likely reach the point of no return within this century, the full transition will take at least a few hundred years.

The impacts of the Greenland ice melt is expected to raise sea levels by up to 20 feet.

Half of the 10 largest cities in the world, including New York City, and one-third of the world’s 30 largest cities are already threatened by this sea level rise. Today, they are home to nearly 1.8 billion people.

Other vulnerable American cities include Miami, Norfolk and Boston.

Photo: siralbertus

3. The West Antarctic ice sheet disintegrates

On the other side of Earth, the West Antarctic ice sheet is also disintegrating. Because the bottom of this glacier is grounded below sea level, it’s vulnerable to rapid break-up, thinning and retreat as warm ocean waters eat away at the ice.

Scientists expect the West Antarctic ice sheet to “tip” this century, and there is evidence that it already began happening in 2014.

However, the entire collapse of the glacier, which would raise sea level by 16 feet, could take a few hundred years.

Photo: BBC World Service

4. El Niño becomes a more permanent climate fixture

The oceans absorb about 90 percent of the extra heat that is being trapped in the Earth system by greenhouse gases. This could affect the ocean dynamics that control El Niño events.

While there are several theories about what could happen in the future, the most likely consequence of ocean heat uptake is that El Niño, a natural climate phenomenon, could become a more permanent part of our climate system.

That would cause extensive drought conditions in Southeast Asia and elsewhere, while some drought-prone areas such as California would get relief.

The transition is expected to be gradual and take around a century to occur – but it could also be triggered sooner.

Photo: Austin Yoder

 5. The Amazon rain forest dies back

Rainfall in the Amazon is threatened by deforestation, a longer dry season, and rising summer temperatures.

At least half of the Amazon rainforest could turn into savannah and grassland, which – once triggered – could happen over just a few decades. This would make it very difficult for the rainforest to reestablish itself and lead to a considerable loss in biodiversity.

However, the reduction of the Amazon ultimately depends on what happens with El Niño, along with future land-use changes from human activities.

Photo: World Bank

 6. Boreal forests are cut in half

Increased water and heat stress are taking a toll on the large forests in Canada, Russia and other parts of the uppermost Northern Hemisphere. So are forest disease and fires.

This could lead to a 50-percent reduction of the boreal forests, and mean they may never be able to recover. Instead, the forest would gradually transition into open woodlands or grasslands over several decades.

This would have a huge impact on the world’s carbon balance because forests can absorb much more carbon than grasslands do. As the forest diminishes, the climate will be affected as will the Earth’s energy balance.

However, the complex interaction between tree physiology, permafrost and fires makes the situation tricky to understand.

Photo: Gord McKenna

Other concerns…

As if that’s not enough, there are a few other tipping events that scientists are also concerned about, but they are even more complex and harder to predict. Examples of such events include the greening of the Sahara and Sahel, the development of an Arctic ozone hole and a chaotic Indian summer monsoon.

How do we keep from tipping over?

We know from measurements that the Earth has had many climate-related tipping events throughout its history. Today’s situation is different, because humans are now driving these changes and the warming is occurring at a faster rate.

But as humans we also have the power to change the trajectory we’re on – possibly in a matter of a few years. We think we know how.

Also posted in Arctic & Antarctic, Extreme Weather, Greenhouse Gas Emissions, Oceans, Plants & Animals| Read 1 Response

On El Niño, snowballs and real climate science

Source: NASA

Just as we thought science was finally taking root, here comes another article claiming that the rise in global temperatures has nearly stopped over the last 15 years. We heard it most recently from the Wall Street Journal.

Never mind that it’s been 30 years since a month was below the 20th century global average surface temperature. Or that climate change is evidenced by clearly visible sea ice and glacial melt. Skeptics support their argument by pointing out, time and time again, how little the Earth has warmed since 1998.

Indeed, the “nearly-stopped warming” may at face value appear to be supported by convincing scientific data. But don’t be fooled: 1998 was an exceptionally warm year thanks to a very intense El Niño, a naturally-occurring phenomenon involving unusually warm water in the Eastern Pacific Ocean.

The change in temperature from 1998 to today, therefore, is not at all a good representation of the long-term trend. It makes the nearly-stopped warming argument no more scientific than a snowball would be in Washington in February.

Selective statistics don't make a trend

Think of it as if you were to use the holiday season as a benchmark for measuring body weight.

If I looked at the weight change I had between Thanksgiving and December 31, a time of year when I usually enjoy lots of good food, the picture would look very different than if my weight monitoring began the week before Thanksgiving. That's because a Thanksgiving start date would be a higher-than-normal weight day, an anomaly.

And, yet, this is exactly what proponents of the nearly-stopped-warming theory are doing.

While it's true that the rate of temperature change has decreased since 2001, they cherry-pick a recent 15-year period, 1998 to 2012, starting with an initial year that is already way above average to prove their point. Of course, these quasi-scientists aren’t transparent about their strategy, so a non-expert would have to dig into the data to realize they are being tricked.

El Niño always a wild card

El Niño, meanwhile, was just doing what niños tend to do: It threw us for a loop.

The one occurring for 10 consecutive months 1997-98 was the most intense ever recorded, making 1998 the hottest year up until that point. (Three years have since broken that record: 2005, 2010 and 2014.)

Scientists have a number of technical and statistical methods for delineating natural from human influences on the temperature record, and apply these tools depending on the research questions they're trying to answer.

But the overall global record is not touched, so if you don't know which years were affected by natural events such volcanic eruptions, it can look noisy and confusing.

This is why we need to look at long-term trends to get the real answers.

This post originally appeared on our EDF Voices blog.

Also posted in Extreme Weather, Greenhouse Gas Emissions, Setting the Facts Straight| Comments are closed

An Urgent Call to Climate Action in the IPCC Synthesis Report

Photo: IPCC

It was released two days late for Halloween, but an international report on the dangers of climate change still has plenty of information about our warming planet that will chill you to the core.

The report is the latest from the Intergovernmental Panel on Climate Change (IPCC).

The IPCC releases a series of reports every six or seven years that assess the latest data and research on climate change. This latest is the Fifth Assessment Synthesis Report—a culmination of three earlier reports in this series.

The Synthesis Report summarizes the physical science of climate change; current and future impacts, vulnerabilities, and adaptation of the human and natural worlds; and mitigation opportunities and necessities.

More than anything else, the report underscores the urgent need for action.

Here are 13 details from the report that illustrate why:

1.  “Warming of the climate is unequivocal… The atmosphere and ocean have warmed, the amounts of snow and ice have diminished, and sea level has risen.”

2.  Changes in climate have impacted all continents and the oceans.

3. The period from 1983 to 2012 was likely the warmest 30-year period of the last 1400 years in the Northern Hemisphere.
Glaciers have continued to shrink almost worldwide. Northern Hemisphere spring snow cover has continued to decrease.

4. Permafrost temperatures have increased in most regions since the early 1980s. Arctic sea-ice has decreased in every season and in every successive decade since 1979.

5. From 1901 to 2010, global mean sea level rose by more than half a foot. The rate of sea-level rise since the mid-19th century has been larger than the mean rate during the previous two millennia.

6. In the future, it is virtually certain that there will be more frequent hot and fewer cold temperature extremes in most areas, on both daily and seasonal timescales. It is very likely that heat waves will occur more often and last longer. The oceans will continue to warm and acidify, and global mean sea level to rise.

7. A large fraction of species face increased extinction risk due to climate change during and beyond the 21st century. Most plant species cannot naturally shift their geographical ranges sufficiently fast to keep up with climate change.

8. Climate change puts humanity at risk from heat stress, storms and extreme precipitation, inland and coastal flooding, landslides, air pollution, drought, water scarcity, sea-level rise, and storm surges. Climate change is projected to undermine food security.

9. “Human influence on the climate system is clear.” Atmospheric concentrations of carbon dioxide, methane and nitrous oxide are unprecedented in at least the last 800,000 years.

10. Continued emission of greenhouse gases will cause further warming and long-lasting changes in all components of the climate system, increasing the likelihood of severe, pervasive and irreversible impacts for people and ecosystems.

11. It is virtually certain that global mean sea-level rise will continue for many centuries beyond 2100, with the amount of rise dependent on future emissions.

12. Many adaptation and mitigation options can help address climate change, but no single option is sufficient by itself. Adaptation can reduce the risks of climate change impacts, but there are limits to its effectiveness.

13. Substantial emissions reductions of greenhouse gases – including carbon dioxide and methane — over the next few decades can reduce climate risks in the 21st century and beyond, increase prospects for effective adaptation, reduce the costs and challenges of mitigation in the longer term, and contribute to climate-resilient pathways for sustainable development.

According to the IPCC Synthesis Report, planet Earth is in pretty dire shape – but the report isn’t hopeless.

Imagine our planet as a patient at a doctor’s office. It’s too late to just stay healthy – we’ve already caught a cold. But we can prevent the cold from deteriorating into pneumonia.

In order to do that, though, we need to act now. We need people, and governments, across the world to join together to reduce greenhouse gas emissions, support adaptation efforts, and help reduce the damages from climate change.

Also posted in Extreme Weather, Greenhouse Gas Emissions, International, News, Policy, Science| Read 1 Response

How scientists linked the California drought to climate change

A drought-stricken vineyard in Napa Valley. Source: John Weiss/Flickr

California has officially entered its fourth consecutive year of drought, and is trapped in its worst water shortage situation ever.

Because we know that human-caused climate change cantrigger and exacerbate drought conditions, media, public officials, California residents and scientists have all been wondering for years if rising global temperatures likely caused or contributed to the current drought in California.

The short answer: Yes, they did.

Weather won’t cooperate

Scientists have suspected for some time now that a certain meteorological condition lies behind the long-lasting California drought. The persistence of a stubborn high-pressure system off the coast has been preventing storm systems from reaching California and instead deflecting them to Alaska and elsewhere.

While weather events are almost always multi-causal, the California drought is largely a result of this atmospheric weather pattern. The question is whether climate change has influenced the development, or sustenance, of this system.

Stanford scientists connected the dots

When destructive events happen, people want to know right then and there what’s going on— whether it’s an epidemic, riot or weather disaster.

But evaluating an extreme weather event for climate change influences is a scientific process that takes several months of computer simulations and statistical techniques. It can frustrate some who demand an answer right away.

Well, the results from several, month-long studies are finally in. Scientists from Stanford have found that the meteorological conditions that have caused the California drought are far more likely to occur in today’s warming world than in one without human-caused emissions of greenhouse gases.

It shows us – ironically and tragically – that the state thatleads the nation in curbing greenhouse gas emissions is right now suffering more than any other from climate change.

California is not alone

The California drought attribution studies are a subset of alarger collection of recently published studies that explain 16 extreme weather and climate events of 2013.

Twenty research teams explored the causes of events such as heat waves in Australia, New Zealand, Korea, Japan, China, and Europe; torrential downpours in Colorado and India, a blizzard in South Dakota, and a cold spell in the United Kingdom.

The studies overwhelmingly indicated that all heat waves were largely attributable to human-caused climate change. One study even suggested that the heat wave in Korea has been made 10 times more likely due to human influence.

The extreme rainfall events in India were concluded to have been more likely in a human-influenced world, but data for assessing precipitation events is rather limited as compared to heat waves. Further, studies concluded that the extreme rainfall event in Colorado, the blizzard in South Dakota, and the cold spell in the U.K. were unlikely to have been influenced by climate change.

Climate change is happening. Now.

So for anyone who may still think that the consequences of climate change are in the distant future, this collection of studies suggest that human-caused climate change is right now causing a crisis in America’s most populous state and the world’s eighth largest economy.

California reminds us that climate change is a major concern for societies everywhere, and that all nations are vulnerable to extreme weather events. It’s time we roll up our sleeves and stop this, once and for all.

This blog originally appeared on EDF Voices 

Posted in Basic Science of Global Warming| Read 4 Responses

Why California thirsts for rain and the East Coast gets soaked

Source: Flickr/Jared Tarbell

If you think the weather’s acting strange, you’re correct. Extreme weather in the United States is trending upward, and human-caused climate change has already been blamed for much of it – most recently in connection with theCalifornia drought.

But along with extreme weather we’re also getting extreme contrasts. What on Earth is going on when New York gets endless rain and San Francisco none, and when one part of the country is freezing while another suffers under record heat?

You guessed it, rising temperatures have something to do with it – and here’s how.

Rain patterns are changing

In the Northeast, the combination of more moisture in the atmosphere from a warmer world and changes in circulation patterns are bringing more rain. In the Southwest, meanwhile, rainfall is suppressed by a northward expansion of high pressure in the subtropics.

The crippling drought now plaguing California is due to a persistent high pressure system off of the coast that is deflecting storms away from the region. A recent study shows that these systems are much more likely to occur with human-caused climate change.

Rain is more intense

Heavy downpours are controlled by cloud mechanisms and moisture content, which are both changing as global temperatures rise. Clouds that can dump a lot of rain are more common in a warmer atmosphere.

More evaporation has led to more moisture in the atmosphere which, in turn, leads to more intense rainfall when it rains. That helps explain why the entire U.S. is experiencing more heavy downpours – even in the drought-stricken West.

Droughts are taking hold

Rain and evaporation will determine how moist the soil will be. So although evaporation is increasing nationwide due to warmer temperatures, higher precipitation in the Northeast yields a net increase in soil moisture in that part of the country.

In the Southwest, on the other hand, the drop in overall precipitation brings drier conditions that spawn or magnify drought. As the soil there dries out, the incoming sunlight will heat the ground instead of evaporating water from the soil. This creates a vicious cycle of more heat and less rain.

Flooding is more common

The potential for flooding, meanwhile, depends a lot on what's going on with the soil. The higher the soil moisture content, the higher the chance that there will be more runoff from rainfall.

Because soil moisture is increasing in the Northeast, flooding events are on the rise. Fortunately for the region, many heavy rain storms occur in the summer and fall when soil moisture is low and the ground can absorb more water.

On the other hand, the sea level has risen by a foot since the 1900s in the Northeast. That, in turn, contributes to more flooding.

Disaster costs are also rising – but there is hope

In 2013, intense storms, severe regional drought, and extreme flooding led to more than $9 billion in disaster costs in the U.S. alone. It’s uncertain what the total bill was if you factor in ongoing agriculture, human health and infrastructure losses from changing weather conditions

Unless we curb emissions of heat-trapping gases, scientists expect these trends to continue and worsen – and the contrast between wet and dry areas of the U.S. will likely become even sharper. Our hope now is that the push for climate action amps up so we can finally set ourselves on a better path for the future.

This post originally appeared on EDF Voices 

Also posted in Greenhouse Gas Emissions, Science| Read 1 Response

"Risky Business" stands out in growing sea of climate reports

Receding beach on North Carolina's Outer Banks. Source: FEMA/Tim Burkitt

(This blog originally appeared on EDF Voices)

This blog post was co-authored by Jonathan Camuzeaux.

Put Republican Hank Paulson, Independent Mike Bloomberg, and Democrat Tom Steyer together, and out comes one of the more unusual – and unusually impactful – climate reports.

This year alone has seen a couple of IPCC tomes, an entry by the American Association for the Advancement of Science and the most recent U.S. National Climate Assessment.

The latest, Risky Business, stands apart for a number of reasons, and it’s timely with the nation debating proposed, first-ever limits on greenhouse gas emissions from nearly 500 power plants.

Tri-partisan coalition tackles climate change

The report is significant, first, because we have a tri-partisan group spanning George W. Bush’s treasury secretary Paulson, former mayor of New York Bloomberg, and environmentalist investor Steyer – all joining forces to get a message through.

That list of names alone should make one sit up and listen.

Last time a similar coalition came together was in the dog days of 2009, when Senators Lindsay Graham, Joe Lieberman, and John Kerry were drafting the to-date last viable (and ultimately unsuccessful) Senate climate bill.

Global warming is hitting home

Next, Risky Business is important because it shows how climate change is hitting home. No real surprise there for anyone paying attention to globally rising temperatures, but the full report goes into much more granular details than most, focusing on impacts at county, state and regional levels.

Risky Business employs the latest econometric techniques to come up with numbers that should surprise even the most hardened climate hawks and wake up those still untouched by reality. Crop yield losses, for example, could go as high as 50 to 70 percent (!) in some Midwestern and Southern states, absent agricultural adaptation.

The report is also replete with references to heat strokes, sky-rocketing electricity demand for air conditioning, and major losses from damages to properties up and down our ever-receding coast lines.

Not precisely uplifting material, yet this report does a better job than most in laying it all out.

Financial markets can teach us a climate lesson

Finally, and perhaps most significantly, Risky Business gets the framing exactly right: Climate change is replete with deep-seated risks and uncertainties.

In spite of all that we know about the science, there’s lots more that we don’t. And none of that means that climate change isn’t bad. As the report makes clear, what we don’t know could potentially be much worse.

Climate change, in the end, is all about risk management.

Few are better equipped to face up to that reality than the trio spearheading the effort; Paulson, Bloomberg and Steyer have made their careers (and fortunes) in the financial sector. In fact, as United States Treasury secretary between 2006 and 2009, Paulson was perhaps closest of anyone to the latest, global example of what happens when risks get ignored.

We cannot – must not – ignore risk when it comes to something as global as global warming. After all, for climate, much like for financial markets, it’s not over ‘til the fat tail zings.

Also posted in Cars and Pollution, Economics, Extreme Weather, Greenhouse Gas Emissions, Health, Jobs, News, Policy| Read 1 Response
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