While the planet warmed steadily at a rate of 0.13° C per decade since 1950, since 1998 it’s been on a hiatus, despite the fact that levels of carbon dioxide, the main greenhouse gas produced by human activities, continued a steady rise, reaching 400 parts per million for the first time in human history in May 2013.

Two researchers from Scripps Institution of Oceanography at UC San Diego discovered the reason for this hiatus, publishing their findings last week in Nature.

The reason for the warming break? Cooling in the eastern tropical Pacific Ocean. The team predicts that long-term global warming will resume when the tropical Pacific switches back to a warm state.

The researchers arrived at their conclusion using innovative computer modeling methods to simulate regional patterns of climate anomalies. This enabled them to see global warming in greater spatial detail, revealing where it has been most intense and where there has been no warming or even cooling.

The current cooling phase began just after a strong El Niño year in 1998. The study considers the tropical Pacific Decadal Oscillation (PDO), a climate cycle that plays out over the course of several decades. Within this large pattern fall El Niño and La Niña, well-known faster cycles that cause shifts in the distribution of warm water in the equatorial Pacific Ocean. While El Niño and La Niña last only a few years, the PDO lasts several decades. The last time it was in a cooling phase—cooling waters in the eastern equatorial Pacific Ocean—it lasted from roughly 1940 to the early 1970s. The researchers are unsure how this long this phase will last.

“That speaks to the challenge in predicting climate for the next few years,” says study co-author Shang-Ping Xie.  “We don’t know precisely when we’re going to come out of [the hiatus] but we know that over the timescale of several decades, climate will continue to warm as we pump more greenhouse gases into the atmosphere.”

“These compelling new results provide a powerful illustration of how the remote eastern tropical Pacific guides the behavior of the global ocean-atmosphere system, in this case exhibiting a discernible influence on the recent hiatus in global warming,” says Dan Barrie, program manager at the NOAA Climate Program Office.

Image: Kosaka, Xie/Scripps

What’s going on with the oceans and what can we do?

As carbon dioxide (CO₂) rises in our atmosphere, the oceans absorb roughly a quarter of the amount. This lowers the pH level in the seawater, making the oceans more acidic. How this affects life in and out of the sea is continually studied.

This week, ocean acidification is the topic of several scientific papers. We thought we’d highlight a few of them here.

Nature Climate Change has two papers—one about the affect of acidification on several different species, and the other on how ocean acidification causes even more global warming.

For the first paper, German researchers surveyed previous studies that dealt with the consequences of ocean acidification for marine species from five animal taxa: corals, crustaceans, mollusks, fish, and echinoderms. By the end, they had compiled a total of 167 studies with the data from more than 150 different species.

Their findings? Different species are affected in different ways and to different extents, but all species are negatively affected by ocean acidification. “Our study showed that all animal groups we considered are affected negatively by higher carbon dioxide concentrations. Corals, echinoderms, and mollusks above all react very sensitively to a decline in the pH value,” says lead author Astrid Wittmann, of the Alfred Wegener Institute.

The second study demonstrates that the negative effects of ocean acidification aren’t just limited to marine life. The authors discovered that rising ocean acidity has the potential to amplify climate warming in general, through the decreased production of a biogenic sulfur compound.

Phytoplankton in the ocean produce dimethyl sulfid (DMS). As DMS is released into the air, it creates atmospheric sulfur—which increases the reflectivity of the atmosphere to incoming radiation, reducing surface temperatures. Warming acidic oceans means the phytoplankton produce less DMS, causing an even warmer planet.

In addition to the Nature papers, Philosophical Transactions of the Royal Society B has an ocean acidification-themed issue this week, with nine papers studying its effects. The papers describe three distinct effects on marine life due to ocean acidification: species interactions, decreased ecosystem functions, and adaptations. Andrew Revkin has a great summary of them on his Dot Earth blog in the New York Times.

“It’s great that some of these papers are looking at entire ecosystems,” says Aaron Pope, the Academy’s sustainability manager who works tirelessly to communicate ocean acidification issues. “There’s been lots of research in the past on individual species impacts, but data on entire natural systems was missing. Now we can start to talk about what will really happen in marine ecosystems as ocean acidification gets worse.”

One paper of the group (from local researchers at San Francisco State University) looks at tiny coccolithophores. These single-celled algae are able to sequester oceanic carbon by incorporating it into their shells, providing ballast to speed the sinking of carbon to the deep sea. The little organisms are central to the global carbon cycle, a role that could be disrupted if rising levels of atmospheric carbon dioxide and warming temperatures interfere with their ability to grow their calcified shells.

This paper might provide a bit of hope among the rest: “At least in this experiment with one coccolithophore strain, when we combined higher levels of CO₂ with higher temperatures, they actually did better in terms of calcification,” says co-author Jonathon Stillman, of SF State.

Here’s to hoping that all of these papers findings will create more awareness of ocean acidification that will lead to more solutions.

Coccolithophore image: Alison R. Taylor/PLoS Biology

As a science writer, I get to write about very interesting subjects. But I never thought David Hasselhoff would become part of my oeuvre.

Hoff crabs are an undescribed species (or two) of the genus Kiwa that live on hydrothermal vents near Antarctica. Named after David Hasselhoff, Hoff crabs sport “hairy” (actually setae) chests—similar to that of the Baywatch, reality and singing star (and general trainwreck).

Hoff crabs live in one of the most extreme environments on the planet: over 2,000 meters under the sea, with no light and very little oxygen, where volcanic vents superheat the water to 380° Celsius and belch out noxious chemicals. They feed by effectively farming bacteria on their hairy chests, then using special comb-like mouthparts to strain off the bacteria so that they can eat them.

“The life of these charismatic crustaceans is a delicate balancing act,” says Nicolai Roterman of Oxford University’s Department of Zoology who gave the crabs the “Hoff” nickname. “They need oxygen to survive, in short supply around the vents, but the bacteria they farm for food depend on chemicals only available near the vents. They exist in the narrow zone where the water from the vents and normal seawater mixes, their challenge is to position themselves close enough to the vents to thrive but not so close that they risk suffocating or getting cooked alive.”

Last week, Roterman and his colleagues published an article in the journal Proceedings of the Royal Society B on the origins of these crabs and their ability to withstand future climate change.

The researchers determined that Hoff crabs split off from their hairier-clawed Kiwa cousins almost 26 million years ago, spreading eastward over undersea ridges from the Pacific, through the Drake Passage between South America and Antarctica, in order to reach vents in the Southern and Indian Oceans.

The split likely happened during a previous natural warming period but doesn’t leave them prepared for future global warming, Roterman says. “If deep-sea ocean oxygen levels fall [with global warming], the amount of oxygen available to these animals, that already live in an oxygen-poor environment at the limits of their physiological tolerance, may drop below the minimum level at which they can survive. They would face the stark choice of suffocate or starve.”

With any luck, they’ll survive into the future, with a longevity that surpasses their namesake.

Image: David Shale

A collection of climate change headlines from this month…

Earlier this month our planet hit a milestone number: 400 parts per million. That’s the amount of carbon dioxide in our atmosphere. From the Elements blog in the New Yorker:

…the number should shake us, if not shock us. We’ve got more carbon dioxide in the atmosphere now than at any point since the Pliocene, when there were jungles in northern Canada.

What this means for life on Earth is measured, modeled and forecasted by scientists every day. But there’s no doubt that the rise in CO2 is causing global warming. Long gone is the argument that scientists disagree on the matter. A paper published two weeks ago in Environmental Research Letters, determines once again that 97% of researchers agree that current climate change is human-caused.

Melting Ice and Rising Seas

We’ve mentioned the effect of melting Arctic sea ice to sea level rise around the world. A study this month demonstrates that continental glaciers (such as the Greenland one, pictured above) will do even more damage. In fact, another study notes that as glaciers melt in Greenland, the locations of Earth’s poles are changing.

Plants and Animals Feel the Effects

Other recent studies examine the effect of climate change on plants and animals around the globe. Traditional wine-growing locations could be too warm to support vines in the near future. Living in the Arctic, polar bears’ immune systems aren’t as robust as organisms living in warmer climes. With the region warming, researchers are concerned that the iconic white bears could be more vulnerable to disease. Another recent paper reveals that fish and other ocean life are moving toward the poles to escape warming seas. Finally, another paper this month explains (once again) that more than half of common plants and one third of animals could see a dramatic decline this century due to climate change.

Extreme Weather

Can we use Australia as a model of the extreme weather we may see as global warming continues? Time will tell. But even though scientists determined that climate change wasn’t a factor for the recent devastating tornado that hit Oklahoma, scientists believe that future tornados could be more damaging thanks to a warming Earth. Deaths due to heat waves in New York will also increase with climate change, according to a paper last week in Nature Climate Change.

Warming Slowdown?

Another paper last week purports that the world is warming slower than expected and that perhaps we will have a second chance. Will we use the time wisely and reduce our CO2 emissions? What do you think?

Image: Michael Studinger/NASA

Happy Earth Day! We would like to share a few recent headlines for you to peruse to ponder and protect our planet…

Pollution
From high to low, all around the world, pollution affects our world. Recent headlines show that “Toxic chemicals are accumulating in the ecosystems of the Himalayas and the Tibetan plateau,” according to Nature. Tiny plastic particles aren’t just trouble in the oceans; the Great Lakes contain millions of microplastics, too. The New York Times’ Dot Earth blog has a short post about the importance of not littering. And National Geographic has an article about how pollution on land can affect marine life like dolphins and local sea otters.

Colorado River
While many U.S. rivers have problems with pollution, the Colorado River’s mismanagement, overuse and drought put it atop the list of Endangered Rivers of 2013. National Geographic has an entire series on the Colorado River delta, and the New York Times has offered both an article and video last week on the region’s hopeful revival.

Drought
Speaking of drought… Do drought-stressed trees cry for help? French scientists are listening for clues. Climate change was not responsible for last summer’s Midwestern drought, according to NOAA, but then what was? And how might we be able to predict future droughts?

Climate Change
Climate change may not have caused of the recent drought, but it is responsible for other devastating events and looming disasters: bumpier flights, more storms, bark beetle plagues, drowned islands, failures in agriculture systems and more extinctions. Researchers are also getting a better handle on tracking climate change through mapping ocean eddies and looking at historic ocean temperatures and air pressure.

Ecology
How do species react to environmental changes? Rapid evolution, according to one study. Another study suggests that endangered species are already doomed. And Nature offers an update on a decades-long study of habitat fragmentation in the Amazon.

Energy
How has energy usage in our country changed over the past two hundred years? NPR has a graph (or four) for that. In response, Scientific American presents a diagram illustrating our potential for future alternative energy use and resources accompanying an article titled, “How to Power the World without Fossil Fuels.” Germany seems to have taken notice—the European country has ambitious renewable plans. But it’s not the only one. The U.S. had a huge year in 2012 for wind power. And, heading across the country soon? How about a solar-powered flight?

Earth Day
Finally, let’s truly celebrate the planet’s holiday with history, maps, jokes about Earth Day, and facts and photos of our beautiful home.

Image: Terra/ASTER/NASA and NASA Earth Observatory

Each fall, monarch butterflies east of the Rockies make the long migration to their overwintering site in Mexico. Scientists have exposed the internal rhythms that tell the butterflies where to go, despite the fact that the site was last visited by their great-grandparents. But how do the butterflies know when it’s time to leave Mexico and head north again?

Researchers at the University of Massachusetts suspected that temperature or daylight had something to do with it, so they collected wild monarchs at the start of their southward fall migration, brought them into the lab, and divided them into three groups. Two of the groups were exposed to the same cooler temperatures they would experience in their overwintering ground in Mexico. In addition, one of these two was also exposed to the same changing light levels they would experience south of the border. For the third group, the temperature remained warm and light levels never changed.

When placed into a flight simulator 24 days later, the first two groups of monarchs began flying northward. The third group, not exposed to cooler temperatures, continued flying southward.

If temperature alone determines when the butterflies start their northward migration, scientists raise concerns about the effects climate change will have on these beauties. “Without this thermal stimulus, the annual migration cycle would be broken, and we could lose one of the most intriguing biological phenomena in the world,” says Steven Reppert. His study, coauthored with Patrick Guerra, appeared last month in Current Biology.

Sadly, on the heels of that study comes a report issued last week on the decline of monarch numbers in Mexico this past winter. The study blames drought in the American southwest and an increase in soy and corn farming. Both are responsible for a loss in the milkweed plants the butterflies rely on for food during their long migrations.

“If people want to help,” says Craig Wilson of Texas A&M University, “they can pick up some milkweed plants right now at local farmer’s cooperative stores and this would no doubt be a big boost to help in their migration journey. It is important to have a national priority of planting milkweed to assure there will be monarchs in the future. If we could get several states to collaborate, we might be able to provide a ‘feeding’ corridor right up to Canada for the monarchs.”

Image: Kenneth Dwain Harrelson/Wikipedia

Four amazing and passionate scientists discussed different aspects of our changing world—wildlife, drought, storms and the tree-ring record—at a press conference titled, “Did Climate Change Cause Superstorm Sandy?”

Remember, these are scientists, not politicians (see more in Andy Revkin’s New York Times blog). They need evidence to see causal effect between one event and another. And for these recent storms and weather patterns, there just isn’t enough evidence. Yet.

But are these researchers glad that these events are focusing Americans’ attention (including the President in his recent State of the Union address) on climate change? Most definitely. Yes.

Here’s what they do know. Climate change is affecting the probability of storms like Sandy and Nemo. There is evidence that in our warming world, severe storms will happen more frequently.

Researchers understand that global warming and other human-related activities are affecting where animals live, move and mate, and when plants bloom.

Scientists also know that temperature increase is one factor in drought. Texas temperatures have risen steeply in just the past 15 years and drought has increased.  And now Texans are talking about climate change, said John Nielsen-Gammon of Texas A&M University. The drought alone didn’t alarm them about climate change, but the decreased water supply has made people and politicians alike take notice.

And the speakers are hopeful and passionate that we’ll start doing something about these effects—reducing fuel emissions, restoring habitats, becoming more aware of climate change.

What do you know and feel? Share with us here.

Midwest drought image: cwwycoff1/Wikipedia

Yesterday, James Hansen of NASA’s Goddard Institute and Thomas Karl of NOAA’s National Climatic Data Center held a joint press conference, describing very similar findings for last year’s warmer than average temperatures around the world. A pdf with their organizations’ side-by-side comparisons is available here.

The average temperature globally in 2012 was about 58.3 degrees Fahrenheit, which is 1.0 F (0.6 C) warmer than the mid-20th century baseline. The average global temperature has increased about 1.4 degrees F (0.8 C) since 1880, according to the new analysis.

The scientists emphasized 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. Each successive year will not necessarily be warmer than the year before, but on the current course of greenhouse gas increases, scientists expect each successive decade to be warmer than the previous decade.

“The U.S. temperatures in the summer of 2012 are an example of a new trend of outlying seasonal extremes that are warmer than the hottest seasonal temperatures of the mid-20th century,” Hansen said. “The climate dice are now loaded. Some seasons still will be cooler than the long-term average, but the perceptive person should notice that the frequency of unusually warm extremes is increasing. It is the extremes that have the most impact on people and other life on the planet.”

In fact, according to Reuters, Americans are feeling the impact of climate change already—consequences that affect “health, infrastructure, water supply, agriculture and especially more frequent severe weather.”

But studies show we can do something about it. Nature Climate Change has an article this week describing how cutting emissions can reduce impacts from climate change. (Read more at Scientific American.) And New Scientist reports that while global talks breakdown over the subject, individual nations are doing something about it. Let’s hope the trend continues.

Want to engage more in the changing climate? Tomorrow Science will host a live chat, “Can We Conquer Climate Change?” Sign in here.

Image: NASA Goddard’s Scientific Visualization Studio