Author Archives: Ilissa Ocko

Huge Antarctic iceberg breaks off. Here's why it worries scientists.

The massive rift in the Antarctic Peninsula's Larsen C ice shelf, photographed by NASA scientists in November 2016. Photo by Stuart Rankin.

This post was co-authored by Mason Fried, a Ph.D. student of glaciology at the University of Texas Institute for Geophysics. It originally appeared on EDF Voices.

Scientists watched with alarm this week as the fourth-largest ice shelf in Antarctica rapidly broke apart, causing an enormous, Delaware-size iceberg to float into the Southern Ocean.

Scientists had been observing the anomalous rift widening across a section of the so-called Larsen C ice shelf for the past several years. Now they’re left with some critical questions: What are this event’s broader consequences for the Antarctic ice sheet, what happens next, and – importantly – what role did climate change play here?

Antarctica: A frontline for climate change

So far, scientists have been hesitant to attribute the Larsen C ice shelf breakup to rising global temperatures.

Indeed, such events – known to scientists as “calving” – occur naturally and are essential for maintaining ice shelf balance. Without them, ice shelves would grow unabated to cover large swaths of the Southern Ocean.

Still, the magnitude and timing of this ice loss warrants attention.

The Antarctic Peninsula, where the Larsen ice shelves reside, has long been viewed as a frontline for climate change. Warming in the peninsula exceeds the global average, glaciers there are retreating, and two other ice shelves on the peninsula already collapsed over the past couple of decades after being stable for thousands of years.

Such changes will help raise global sea levels by 3 to 6 feet by 2100, projections show, affecting dense coastal communities along our Eastern seaboard and across the globe.

Ice breakup starts chain reaction

We do know that this latest ice separation could set in motion a string of chain reactions that further destabilize the ice shelf and surrounding glaciers, and ultimately contribute to global sea level rise.

Ice shelves are floating extensions of grounded glaciers and ice sheets that, importantly, buttress and impede inland ice flow. When an ice shelf collapses or becomes weaker, this defense disappears, allowing inland glaciers to accelerate downslope and transport more ice to the ocean, which can quickly affect sea level.

Scientists worry that the remnant Larsen C ice shelf will now be at considerable risk of further breakup.

The new ice berg reduced the ice shelf area by more than 12 percent when it broke off, leaving behind an ice shelf that is inherently unstable. This can, in turn, trigger new ice cracks and rifting, and cause more icebergs to break off – further increasing the possibility of runaway ice loss amid rising global temperatures.

Whether or not this latest calving event will be attributed to climate change, it’s safe to say that it will make the region more vulnerable to the impacts of global warming.

Climate change caused 2002 ice shelf collapse

The Larsen C ice shelf, named for a Norwegian whaling vessel captain who sailed the Southern Sea in the late 1800s, has two smaller northern neighbors known as Larsen A and Larsen B – both of which collapsed in the past 23 years.

Those events taught us that ice sheets, landscapes we used to think of as stable and slow to change, can actually transform rapidly.

The Larsen B collapse was particularly dramatic, with nearly the entire ice shelf disintegrating during a three-week period in 2002 after remaining stable for at least 10,000 years.

The speed of that event was unprecedented and attributed directly to increasing atmospheric warming, although rising ocean temperatures and long-term ice loss from surrounding glaciers may also have played a role.

A hint of what’s to come?

After the Larsen B shelf collapse, researchers observed dramatic increases in glacier speed, thinning and ice transfer to the ocean.

Some researchers are already drawing parallels between this week’s Larsen C collapse and the series of events that led to the eventual collapse of Larsen B. The latter experienced a similar large calving event in 1995 that foreshadowed further retreat and widespread disintegration in 2002.

While it remains to be seen if and when Larsen C will meet the same fate, warning signs are already in place. What’s happening to the Larsen ice shelves could, in fact, be a proxy for what’s to come across even larger sections of the Antarctic ice sheet unless we take action to slow warming.

Posted in Arctic & Antarctic, News, Science| Comments are closed

Take these first steps to lower your impact on climate change

Happy Earth Day

The average household in the United States emits almost 100,000 pounds of carbon dioxide per year. That is about the same weight as 10 adult African elephants.

Earth Day is tomorrow, and at this time of the year, many of us are thinking about those kinds of facts. We wonder how we can personally help the climate by reducing our individual impacts.

A simple internet search will yield a laundry list of actions that may be overwhelming, and often will be far less than satisfying. You may find suggestions that are not indicative of the actual size of your impact (turning off your lights versus not flying from east to west coast, for example – they are not equivalent). You may also find information that is irrelevant to your specific lifestyle (for example, the recommendation to cut out meat when you are already a vegetarian).

Because each of our lives is unique (click here to see how carbon footprints vary by zip code), we really need to have a good understanding of our personal and professional impacts on the climate before we can determine good actions to take, and choices to make, to reduce those impacts.

Here is a table with some great resources, to help you get started:

 

PERSONALPROFESSIONAL
Calculate your carbon footprint AND determine specific actions you can take to reduce your impactUse this calculator to:

1. Determine your personal carbon footprint (broken down by travel, housing, food, goods, and services)

2. Develop your unique action plan tailored to your personal impacts (includes emissions saved, dollars saved, and upfront costs)
Use this calculator to:

1. Determine your business carbon footprint (broken down by travel, facilities, and procurement)

2. Develop your unique action plan tailored to your business impacts (includes emissions saved, dollars saved, and upfront costs)
Make better choicesLearn how to save energy and money at home, on the move, at the store, in the yard, at the curb, and at work
Learn how to be more energy efficient at home, in buildings, and in plants, and to buy more efficient products and new homes.
Posted in Cars and Pollution, Energy, Greenhouse Gas Emissions, Partners for Change, Science| Comments are closed

How Do We Know That Humans Are Causing Climate Change? These Nine Lines of Evidence

While most Americans acknowledge that climate change is happening, some are still unsure about the causes.

They are often labeled “climate skeptics,” but that label can cause confusion or even anger.

Isn’t the nature of science to be skeptical? Isn’t it good to question everything?

Yes, but —

Here’s what is getting lost in the conversation:

Scientists have been asking these questions for nearly 200 years. The scientific community has been studying these questions for so long that collectively they have amassed an overwhelming amount of evidence pointing to a clear conclusion.

A similar situation is smoking and cancer. Nowadays, no one questions the link between smoking and cancer, because the science was settled in the 1960s after more than 50 years of research. The questions have been asked and answered with indisputable evidence.

We can think of the state of human activities and climate change as no different than smoking and cancer. In fact, we are statistically more confident that humans cause climate change than that smoking causes cancer.

Our confidence comes from the culmination of over a century of research by tens of thousands of scientists at hundreds of institutions in more than a hundred nations.

So what is the evidence?

The research falls into nine independently-studied but physically-related lines of evidence, that build to the overall clear conclusion that humans are the main cause of climate change:

  1. Simple chemistry that when we burn carbon-based materials, carbon dioxide (CO2) is emitted (research beginning in 1900s)
  2. Basic accounting of what we burn, and therefore how much CO2 we emit (data collection beginning in 1970s)
  3. Measuring CO2 in the atmosphere and trapped in ice to find that it is indeed increasing and that the levels are higher than anything we've seen in hundreds of thousands of years  (measurements beginning in 1950s)
  4. Chemical analysis of the atmospheric CO2 that reveals the increase is coming from burning fossil fuels (research beginning in 1950s)
  5. Basic physics that shows us that CO2 absorbs heat (research beginning in 1820s)
  6. Monitoring climate conditions to find that recent warming of the Earth is correlated to and follows rising CO2 emissions (research beginning in 1930s)
  7. Ruling out natural factors that can influence climate like the Sun and ocean cycles (research beginning in 1830s)
  8. Employing computer models to run experiments of natural vs. human-influenced “simulated Earths” (research beginning in 1960s)
  9. Consensus among scientists that consider all previous lines of evidence and make their own conclusions (polling beginning in 1990s)

(You can also see these nine lines of evidence illustrated in the graphic below)

Skeptics sometimes point to the last two supporting lines of evidence as weaknesses. They’re not. But even if you choose to doubt them, it is really the first seven that, combined, point to human activities as the only explanation of rising global temperatures since the Industrial Revolution, and the subsequent climate changes (such as ice melt and sea level rise) that have occurred due to this global warming.

The science is settled, and the sooner we accept this, the sooner we can work together towards addressing the problems caused by climate change – and towards a better future for us all.

 

(Click here for a pdf version of the graphic)

 

Posted in Basic Science of Global Warming, Greenhouse Gas Emissions, Science, Setting the Facts Straight| Read 39 Responses

The Impacts of Climate Change on Human Health – a Sobering New Report

We have even more information this week about the ways climate change poses a threat to human health.

The U.S. Global Change Research Program just released its newest report—The Impacts of Climate Change on Human Health in the United States. This scientific assessment is the culmination of three years of work by hundreds of experts, and builds on the more general National Climate Assessment released in 2014.

The report concludes that every American is vulnerable to the health impacts associated with climate change.

Health Threats from Climate Change graphic

Graphic created by Ilissa Ocko, EDF Scientist

Scientists have known for decades that climate change threatens human health via excessive heat, worsened air quality, water related illnesses, food safety, diseases transmitted by pests like fleas and mosquitos, and mental stress. The new report thoroughly characterizes our current understanding of these impacts.

Because scientific understanding has advanced significantly in recent years, the authors also reviewed new information and insights from several recent scientific, peer-reviewed publications and other publicly available resources.

For example, new data revealed that the Ragweed season has grown by as much as 27 days in the central U.S. from 1995 to 2011, and the incidence of Lyme disease in the Northeast has doubled from 2001 to 2014, both consistent with warming trends.

Recent modeling studies have also improved quantification estimates of and confidence in projected health outcomes from climate change. By midcentury, scientists project that there will be as many as thousands of additional ground-level ozone (smog) related illnesses and premature deaths, and the majority of the western U.S. will have a 500 percent  increase in the number of weeks with risk of very large fires. By the end of the century, scientists project that there will be an additional 27,000 summertime heat-related deaths annually in over 200 U.S. cities (that are currently home to 160 million people), and harmful toxin-producing algal blooms could develop up to two months earlier and persist for up to two months longer.

Through climate and weather changes and disruptions to ecosystems and societal systems, here are the main concerns about climate change impacts on human health:

  • Temperature Related Death and Illness — Future climate warming could cause up to tens of thousands of additional deaths each year from heat in the summer, from loss of ability to control internal temperature, and worsened chronic cardiovascular and respiratory diseases
  • Air Quality Impacts — The future could include limited productivity at work and school due to exacerbated ground-level ozone (smog) health impacts from modified weather patterns conducive to ozone formation, and worsened allergy and asthma conditions from more airborne pollen and longer pollen seasons
  • Vectorborne Disease — The seasonality, distribution, and prevalence of vectorborne diseases, including Lyme disease and West Nile virus,  may change with changing temperature and rainfall patterns due to altered geographic and seasonal distributions of mosquitoes, ticks, and fleas
  • Water-Related Illness — Risk of exposure to illnesses increases as the growth, survival, spread, and toxicity of water-related pathogens and toxins is impacted by temperature and extreme rainfall events, and aging water infrastructure is vulnerable to failure with extreme events and storm surges
  • Food Safety, Nutrition, and Distribution — Rising temperatures, changing weather patterns, and extreme events have consequences for contamination, spoilage, and the disruption of food distribution, whereas higher carbon dioxide levels lower nutritional value of crops despite boosting plant growth
  • Extreme Weather — Fatalities, injuries, and infrastructure damages are imminent with increases in the frequency and/or intensity of extreme precipitation, hurricanes, coastal inundation, drought, and wildfires
  • Mental Health and Well-Being — Mental health conditions may develop with exposure to disasters or worsen by extreme health

Overall, the report is a sobering portrait of the risks we face because of climate change — and it underscores the urgency for climate action.

 

 

 

Posted in Basic Science of Global Warming, Extreme Weather, Health, News, Plants & Animals, Science| Comments are closed

3 reasons the Zika outbreak may be linked to climate change

The regions that the Zika virus outbreak has struck hardest, such as Brazil and Colombia, also happen to be areas that are currently plagued by hotter-than-usual temperatures.

So is there a connection?

The ways that virus-carrying mosquitoes change their behavior with warmer temperatures may, in fact, point to a link between the Zika outbreak and climate change like the one that exists with malaria, Lyme Disease and other ills.

While it’s important to remember that it’s probably a combination of reasons for the current Zika virus outbreak – including movement of people and available breeding grounds – there are three ways in particular that warmer weather may be contributing to the crisis:

graphic_v3 (2)

1. Hotter temperatures make mosquitoes hungrier

Female mosquitoes require blood meals for reproduction. Along with many cold-blooded animals, mosquitoes feed more frequently with higher temperatures. The more they eat, the likelier they are to get infected and spread the disease.

2. Warm air incubates the virus faster

A virus must incubate inside a mosquito before the mosquito becomes infectious. That takes about 10 days, roughly a mosquito’s lifespan, so the mosquito will often die before it can spread the disease.

But hotter temperatures speed up the incubation process in the cold-blooded mosquito, because the virus can replicate faster. This means that the mosquito will be alive longer while infectious, thus having more time to transmit the disease.

3. Mosquito territory expands as the climate warms

Mosquitoes flourish in warm climates, restricting their range based on temperature. But with climate change, plants and animals are moving northward and upward, and we know mosquitoes do the same as new areas become warmer and a suitable habitat.

As mosquitoes expand their range, they can introduce diseases to populations that otherwise would have been safely out of reach. The distribution of the Zika-carrying mosquito, in particular, has wildly increased over the past few decades, which have also been the hottest decade on Earth in more than 1,000 years.

In fact, the current epidemic took off in 2015, the hottest year in South America and globally since record-keeping began 136 years ago.

The links between mosquitoes and temperature are scientifically clear, and it’s possible that climate change may now be playing a role in the spread of the Zika virus, a disease suspected of causing serious birth defects.

To know for sure, and to help nations deal with the outbreak, more research is needed to tease out the specific causes of this global catastrophe.

This post originally appeared on our EDF+Voices blog.

Posted in Health, News, Plants & Animals, Science| Comments are closed

Climate Change and Millennials – An Entire Lifetime of Warmer Than Average Temperatures

While reading the announcement that 2015 had broken – indeed, shattered – the hottest year on record set by 2014, there was one fact that really made things personal: we have now had 31 straight years since a single month was cooler than the twentieth century global average temperature. That means that I have never lived through a month that wasn’t warmer than average – never once in my lifetime.

My entire career as a climate scientist is focused on reducing the threat of global warming, and yet I have never even been alive at a time when the climate was stable. I technically don’t even know what normal is.

Warmest Years on Record graphic

So on one hand, you could say that I don’t even know what I am fighting for. On the other hand, I’ve been afforded two unique opportunities because I’ve lived in the shadow of global warming my entire life.

First, because I’ve grown up at a time when heat records are broken over and over again, I was aware of this worldwide crisis during those impressionable and important “pick a major” years of college. I was thus able to set myself on a career path shaped by climate change from the get-go, rather than later on in life once I was already an established professional in something else.

Second, because my elder colleagues have already identified – with extreme confidence – that humans are the main cause of climate change, I’ve been able to focus on solutions from the get-go, and not just causes and impacts. I have thus benefitted from previous scientific research because I could explore avenues to address climate change, because if humans are the cause, then we are also the solution.

And it’s not just me; there is now an entire generation of young people motivated and empowered to do something about climate change. We – almost the entire millennial generation – have never lived in a world without global warming.

Perhaps for similar reasons to mine (and/or because we think we’re special), my generation has shown a propensity for not just caring about climate change, but doing something about it. Whether on their campuses of their schools or the communities where they live, my generation is showing that they want solutions. In fact, eighty-percent of millennials support cleaner energy in the U.S., regardless of party affiliation.

For this reason among others, I am more hopeful about our future than ever before. Climate change has been impacting my generation our whole lives, but it doesn’t have to stay that way. We didn’t ask for this challenge, but I truly believe we’ll be able to rise up to meet it.

Posted in Basic Science of Global Warming, Extreme Weather, Greenhouse Gas Emissions, News, Science| Read 1 Response
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