Tuesday, March 31, 2009

Are there really 93 months to act?

Communicating the urgency of climate change is an ongoing challenge. The problem is the time lag between GHG emissions and the climate impact, what we often refer to as "committed warming". There's also a "societal" warming commitment, caused by the lag between a decision to control emissions and the actual emissions control. That's why Jim Hansen protests the construction of new coal-fired power plants: they are a promise of future emissions and thus increase the societal warming commitment.

The latest approach is to provide estimates of how much time we have "left" to avoid dangerous climate change. Take Andrew Simms in the Guardian (please?):

Whatever the mistakes that allowed this situation to arise, there is growing international consensus that the best way out is via a green new deal policy package. Parts of the UK economy are in freefall with unemployment rising rapidly. At the same time, with less than 100 months to go before the world enters a new, more dangerous phase of global warming, there is an urgent need for the rapid environmental transformation of the economy.

100 months? I don't recall that in the IPCC. Simms' evidence is summarised here and here - there's even a ticking clock, a la the Fox TV show 24.

We found that, given all of the above, 100 months from today we will reach a concentration of greenhouse gases at which it is no longer "likely" that we will stay below the 2C temperature rise threshold. "Likely" in this context refers to the definition of risk used by the IPCC. But, even just before that point, there is still a one third chance of crossing the line.

Is this a useful PR tool? Or, in the desperation to encourage action on climate change, are the "100 hundred months" crowd causing more harm by providing false certainty in future predictions? For example, what will happen in January, 2017 if the world has not begun seriously curbing emissions -- or if it has?


Sunday, March 29, 2009

The Canadian emissions story

Earth Hour dipped electricity use in British Columbia by 1.1%. Again, a nice gimmick to raise awareness about energy use, but far far far from what's needed to tackle greenhouse gas emissions in Canada (right)

The Canadian government published a report earlier this year documenting the trends in greenhouse gas emissions from 1990, the first reporting year, up until 2006. The data reveals a lot of interesting and surprising trends and can answer some of the questions about the contribution of individual Canadian provinces raised by my recent post on change in per capita GHG emissions around the world.

Between 1990 and 2006, Alberta passed Ontario as the largest total emitter of greenhouse gases [top chart]. Alberta is responsible for 33% of emissions, despite housing only 11% of the Canadian population. Alberta alone was responsible for just over half of the total increase in GHG emissions between 1990 and 2006 [second chart].

The #2 province Ontario is responsible for 27% of national emissions but has almost four times the population. Therefore the per capita emissions in Ontario are 15 t CO2-eq / person, hardly a lofty goal, still more than three times that of China, but one quarter that of Alberta.

Saskatchewan is fourth in total emissions at 10% of national emissions, only slightly behind Quebec, despite housing only one-seventh of the population of la belle province. Saskatchewan’s carbon-intensive economy has become even more so over the past two decades. Thanks to a growing uranium and potash industries, expansion of oil production and reliance on coal power, the province of only one million people was responsible almost a quarter of the national increase in GHG emissions from 1990 to 2006.

Quebec, on the other hand is Canada’s pocket of Europe in more ways than one. Thanks to a heavy reliance on hydro power, la belle province’s per capita GHG emissions of 10.7 t CO2-eq/person are more in line with Europe than the rest of North America. Lower heating demands and increased reliance on hydro power helped make Quebec the one Canadian province where GHG emissions decreased (by 1%) between 1990 and 2006. Note the word province; this is not to slight the Yukon, Northwest Territories and Nunavut, where GHG emissions decreased 17% over the same time period.

Per capita emissions [third chart] were relatively steady across much of the country between 1990 and 2006: there was a 12% decrease in Ontario, a 10% decrease in Quebec, and a 7% increase across the Maritimes. The big discrepancy is between Alberta and Saskatchewan. Alberta’s population growth kept pace with the growth in emissions – people came from other provinces to work in the oil sands operations. Saskatchewan, on the other hand, has seen a 67% increase in per capita emissions due to a declining population (this trend began to reverse in the past few years).

The carbon-intense nature of the economies of Alberta and Saskatchewan is best illustrated by a chart of the GHG emissions intensity: the GHG emissions per $ of GDP. This is shown in the final chart to the right (2006 only). In 2006, creating one dollar of GDP in Alberta required over five times the GHG emissions as in Ontario, over six times the GHG emissions as in Quebec. The high emissions intensity of Saskatchewan and Alberta leads to the interesting results that the emissions intensity appears to decrease with population.
There’s likely some economic logic to that pattern: for example, areas of higher populations and large cities are more “efficient” overall, and resource extractive industries tend to be located in areas of lower population.

These are just some of the broad patterns in the GHG data. There is much much more to analyse and discuss.


Saturday, March 28, 2009

Lights dim around the world for Earth Hour

So far, aside from the stupid comments from Bjorn Lomborg ("the use of candles during the hour could actually produce more emissions than electric lights"), Earth Hour has been positively received in most of the world.

BONN, Germany (AP) — From an Antarctic research base to the Great Pyramids of Egypt and beyond, the world switched off the lights on Saturday for Earth Hour, dimming skyscrapers, city streets and some of the world's most recognizable monuments for 60 minutes to highlight the threat of climate change.

Time zone by time zone, nearly 4,000 cities and towns in 88 countries joined the event sponsored by the World Wildlife Fund to dim nonessential lights from 8:30 p.m. to 9:30 p.m.

An agreement to replace the Kyoto Protocol, which expires in 2012, is supposed to be reached in Copenhagen, Denmark, this December, and environmentalists' sense of urgency has spurred interest in this year's Earth Hour. Last year, only 400 cities participated; Sydney held a solo event in 2007.

In Bonn, WWF activists held a candlelit cocktail party on the eve of a U.N. climate change meeting, the first in a series of talks leading up to Copenhagen. The goal is to get an ambitions deal to curb emissions of heat-trapping gases that scientists say are dangerously warming the planet.

"People want politicians to take action and solve the problem," said Kim Carstensen, director of the global climate initiative for WWF, speaking in a piano bar bathed by candlelight and lounge music.

Organizers initially worried enthusiasm this year would wane with the world focused on the global economic crisis, Earth Hour executive director Andy Ridley told The Associated Press. But he said it apparently had the opposite effect.

"Earth Hour has always been a positive campaign; it's always around street parties, not street protests, it's the idea of hope, not despair. And I think that's something that's been incredibly important this year because there is so much despair around," he said.

The Chatham Islands, a small chain about 500 miles (800 kilometers) east of New Zealand, switched off its diesel generators to officially begin Earth Hour. Soon after, the lights of Auckland's Sky Tower, the tallest man-made structure in New Zealand, blinked off.

At Scott Base in Antarctica, New Zealand's 26-member winter team resorted to minimum safety lighting and switched off appliances and computers.

In Australia, people attended candlelit speed-dating events and gathered at outdoor concerts as the hour of darkness rolled through. Sydney's glittering harbor was bathed in shadows as lights dimmed on the steel arch of the city's iconic Harbour Bridge and the nearby Opera House.

And in Egypt, the Great Pyramids darkened, as did the Sphinx.

To the West, floodlights at the Acropolis in Athens were switched off and an outdoor concert was staged on an adjacent hill, which many Athenians approached in a candlelight procession. The Athens International Airport switched off the lights on one of its two runways.

In that other great ancient city, Rome, the Colosseum and St. Peter's Basilica were plunged into darkness.

In Paris, the Eiffel Tower, Louvre and Notre Dame Cathedral were among 200 monuments and buildings that went dark. The Eiffel Tower, however, only extinguished its lights for five minutes for security reasons because visitors were on the tower, said WWF France spokesman Pierre Chasseray.

"Above all in the current economic crisis, we should send a signal for climate protection," said Klaus Wowereit, the mayor of Berlin, one in a handful of German cities switching off lights at city halls and television towers for Earth Day for the first time.

Meanwhile, the Swiss city of Geneva switched off the lights on theaters, churches and monuments. Among them were the Reformation Wall, where floodlights normally illuminate 10-foot (three-meter) statues of John Calvin and other leaders of Protestantism. The city's motto engraved on either side of the statues is: "After darkness, light."

All of Spain's 52 provincial capitals turned off some lights an hour after sunset, silhouetting unlit landmarks such as the royal palace and parliament in Madrid, the Guggenheim museum in Bilbao, and the Alhambra palace in Granada against darkening dusk skies.

A key 2010 football World Cup qualifier against Serbia posed a dilemma for Romanians. "Shall we watch the match or turn off the lights?," the 7plus daily asked in its main front-page headline.

The U.N. headquarters in New York and other facilities were dimming their lights to signal the need for global support for a new climate treaty.

U.N. Secretary Ban Ki-moon called Earth Hour "a way for the citizens of the world to send a clear message: They want action on climate change."

China participated for the first time, cutting the lights at Beijing's Bird's Nest Stadium and Water Cube, the most prominent 2008 Olympic venues.

In Bangkok, the prime minister switched off the lights on Khao San Road, a haven for budget travelers packed with bars and outdoor cafes.

Earth Hour organizers say there's no uniform way to measure how much energy is saved worldwide.

Earth Hour 2009 has garnered support from global corporations, nonprofit groups, schools, scientists and celebrities — including Oscar-winning actress Cate Blanchett and retired Cape Town Archbishop Desmond Tutu.

McDonald's Corp. planned to dim its arches at 500 locations around the U.S. Midwest. The Marriott, Ritz-Carlton and Fairmont hotel chains and Coca-Cola Co. also planned to participate.


Friday, March 27, 2009

Will people participate in Earth Hour?

The optimistic organizers are hoping one billion people will switch off their lights tomorrow at 8:30 pm [your] local time. All sorts of different towns, cities and businesses are taking part. For just one example, tomorrow night's LA-Nashville hockey game is being played early so as not to conflict with the hour of darkness.

It is a gimmick, sure, but a surprisingly effective one. Last year, Earth Hour led to a measurable drop in electricity demand in participating Canadian, Australian and New Zealand cities last year. That won't solve climate change. It does at least make people think. A poll taken after last year's Earth Hour showed a majority of Canadians - across party lines - think it should happen more often.


Best "greenwashing" of the year?

And now for something completely ridiculous:

Pepsi is releasing a "Eco-fina", a more ecologically friendly version of the company's Aquafina bottled water. The Eco-Fina bottle is lighter and contain 20% less plastic. Never mind that the new light bottles will still contain plain-old tap water that has been subject to an unregulated and unnecessary purification process.

One may want to applaud the development of a new, more efficient beverage container. How about reserving that new technology for beverages that actually require a container?

This snippet from a 2006 article in the Globe and Mail neatly summarizes the inanity of the bottled water industry, especially the bottled water sold by the major beverage companies like Pepsi and Coke:

A one-litre bottle of Dasani brand water, sold at a Toronto supermarket recently for $1.59, retails for about 3,000 times the price of a litre of municipal water from nearby Brampton, where the container was filled. Coca-Cola Bottling Co. filters the municipal water and then adds minerals to improve its taste. Federal product labelling laws do not require bottlers to indicate that their products originally were tap water, but do require companies to say whether it is spring or mineral water.


Monday, March 23, 2009

A new online voice on the coral reef crisis

For the past few months, the site known as The Reef Tank has been educating the enthusiastic community of coral reef aquarium owners about marine science and the crisis facing the world's coral reefs. Their blog features an interview with me about my work on climate change and coral reefs, as well as some informative posts about ocean acidification and coral bleaching by coral reef expert John Bruno.


Sunday, March 22, 2009

A mea culpa by the Washington Post, or not

The Washington Post has published Chris Mooney's intelligent critique of the mistaken claims about climate science in recent columns by the paper's own George Will. Here's the take home message:

Readers and commentators must learn to share some practices with scientists -- following up on sources, taking scientific knowledge seriously rather than cherry-picking misleading bits of information, and applying critical thinking to the weighing of evidence. That, in the end, is all that good science really is. It's also what good journalism and commentary alike must strive to be -- now more than ever.

Many online voices including Joe Romm and Mooney himself are applauding the Post for publishing an opinion piece that criticizes its own opinion columnist. While we applaud the implicit mea culpa, let's not forget that original fault here lies with the newspaper. A real victory will be an assurance from the Post that the editorial board will fact-check and properly vet opinion pieces, even those written by a star syndicated columnist.

Mooney's right that scientists apply critical thinking to the weighing of evidence. Guess what? We still make mistakes and misinterpret results. That's why we are required to state our methods. And that's why we have peer review.

The same should be true of the editorial page. Surely, we should expect better of a columnist like Will, that he will follow up on sources, properly weigh evidence and double check all his sources and facts. But incorrect claims about climate science or whatever subject are bound to happen, intentional or not. That's why you have editors. That's why you have an editorial process.

Don't get me wrong. George Will should be criticized for the content of his columns. As should Lorne Gunter for the unsubstantiated drivel in his climate-related columns that appear in Canada's National Post. The thing is, even if Will or Gunter changes their ways, there will be some other columnist willing to cherry-pick misleading bits of information. It's great to see an opinion piece that defines good science journalism. Now let's see an editorial policy that does the same.


Friday, March 20, 2009

Recent changes in per capita emissions

As we approach the pivotal UN climate meetings in Copenhagen this December, there will be plenty of discussion about the progress, or lack thereof, on greenhouse gas emission reductions among Kyoto signatories. The story is usually told with the graph to the write, compiled from UN Framework Convention on Climate Change (UNFCCC) data. Shown is the change in greenhouse gas emissions (excluding land use change) by country between 1990, the baseline year for Kyoto, and 2006. The emissions are expressed as CO2-“equivalent”, an easy catch-all in which the totals for non-CO2 greenhouse gases like methane are converted into equivalent amounts of CO2. {click on the chart for a better look}

It is no secret at this point that the US and China are the largest emitters of greenhouse gases. China is thought to have matched or surpassed the US in total GHG emission in the past couple years. The comparison, of course, is unfair because there are four times as many people in China. A more equitable metric – per capita emissions – finds that the average American, Canadian and Australian is responsible for more than four times the GHG emissions of the average Chinese citizen.

The importance of describing GHG emissions per capita, rather than only total emissions by country, appears to be widely appreciated at this stage [although one might argue not widely enough, given some of the pre-Copenhagen rhetoric out there in the ether]. However, most of the cursory analyses and discussion of recent trends in GHG emissions in the media and online have focused on the total emissions metric. A lot of Canadians can repeat the statistics on emissions growth, and the difference between current emissions and the Kyoto target. But how have per capita emissions changed? {Continued after the jump}

Here’s one reason this matters. Upon first glance at the total emissions number, European nations appear to have been far more successful at controlling GHG emissions than the rest of the Annex I nations. A common criticism of claims of “progress” in Europe is that most European nations are experiencing very low population growth, even negative growth in the case of some of the former Eastern Bloc nations.

The second chart shows some crude analysis of this question. The chart shows the change in per capita emissions from 1990 to 2005, expressed in CO2-equivalent per capita [this was calculated from the UNFCCC GHG emissions data and population data from the United Nations]. Countries in red experienced an increase in per capita emissions. Another way of thinking about this is that, all else being equal, the change in GHG emissions in these countries is greater than can be explained by population growth alone.

The data illustrates a couple interesting trends. First, the argument that European nations have achieved more progress in slowing or reversing emissions [than the US and Canada] purely because of demographic change is not borne out by the national data in most cases. Of course, a more detailed analysis may find ways in which demographics have played an important role. Per capita emissions decreased in France, Germany, the UK, Sweden, Denmark, the Netherlands, Switzerland, Norway and Belgium, in each case by a greater percent than the total emissions decreased. [for now, I’ll exclude the former eastern Bloc nations from this discussion, since the emissions reduction there were driven more by the collapse of former Soviet industries than the slow or negative population growth].

Second, per capita emissions also declined slight (2%) in the US from 1990 to 2005 [note: no population data was available for 2006]. If Canadians need any more evidence that we and our government have failed miserably at addressing greenhouse gas emissions, as required under the Kyoto Protocol, this is it. Canada’s per capita emissions have risen 6% over a period in which America’s per capita emissions have dropped by 2%. No doubt, the addition of 4.6 million people to Canada between 1990 and 2005 has influenced GHG emissions. However, the country’s total GHG emissions are still 6% higher than could be expected from population growth alone.

It is possible that the economic crisis will change this story – in the Canadian case, the drop in resource and oil prices has slowed industrial activity in the oil sands and other regions, perhaps leading to slower increase, or even a decrease in national GHG emissions.I suspect that all the jumping up and down earlier last year about global GHG emissions being “ahead” of the scenarios used by the IPCC will go for naught, as the economic crisis is surely blunting GHG emissions growth.


Tuesday, March 17, 2009

Does Canada's minister in charge of science question evolution?

This story is just horrifying. Will someone please tell it is a joke?


Saturday, March 14, 2009

George Will and the lessons we can learn from Greenland

Followers of the climate news online are no doubt aware of the web-plosion caused by an error-filled column by Washington Post op-ed columnist George Will.

Will's Feb 13th op-ed drew online outrage and letters to the Post ombudsman, which begat an article by the NY Times Andrew Revkin contrasting Will's multiple, egregious errors with an erroneous slide used by Al Gore in a climate presentation, which begat heated [and deserved!] criticism of Revkin for drawing false equivalence, which begat spats about the people like Matthew Nesbit quoted in Revkin's article, which together begat another equally dubious Will op-ed, which begat more outrage, and which all eventually begat yet another a set of posts dissecting or defending Roger Pielke, who is like the black hole of the climate blogs, eventually absorbing all the energy of the surrounding community.

There are many important things to take away from this dispute, not the least of which being that even the most reputable newspapers clearly do not properly fact-check opinion pieces (ie. Will). The problem with Will's climate skeptic talking points - make no mistake, these are oft-repeated points - is not just the numbers. It is the lesson you draw from those numbers.

Case in point, Will's recent comments about the Vikings:

Now, it seems to me there is a 100 percent certainty that at any moment the planet is warming or it is cooling. That's what it does. There are cycles well-recorded through history. The climate was once warm enough for Greenland to be called "Greenland" for a reason -- the Vikings farmed there.

No doubt, there are factual and contextual concerns with this statement. First of all, the island is called Greenland for a number of possible reasons, including i) the southern coastal regions where the Norse landed is green; it is now, it was then, and ii) green may be a misrepresentation of 'grunt', the Norse word for ground. Second of all, yes, the Vikings did in fact farm in Greenland, the Greenlandic people think climate change will allow them to expand farming once again. One shouldn't get carried away with the term "farm". The Viking weren't growing corn and soybeans and tomatoes and lettuce -- they grew hay to feed to animals.

The real issue here is what we can learn from history. Will and others skeptical of the human role in climate change repeat this meme about Greenland presumably to advance two related points:
a) that the climate varies naturally over time,
b) that climate change scientists ignore point (a).

Point (a) is a red herring. Of course the climate varies naturally over time. However, just because there is natural climate variability doesn't mean that other forces, like greenhouse gas emissions, have no effect on the climate, or that current trends are due to natural variability. That's why we do research, that's why we build models based on physics and chemistry.

Point (b) is wrong, and very telling.

The Norse in Greenland is one of the most important case studies in climate and history. In my course of the global climate system, I spend a half a lecture talking about the what happened to the Norse settlements in Greenland.

Greenland was settled around 985 AD by the Norse. Other than the Inuit and the modern Danes, this was the only successful human settlement of Greenland. The environment was too harsh for cereal cultivation so the Norse relied on pastoralism, growing hay for sheep and cattle, and trade with other Norse colonies.

The Norse settlements flourish until the mid-1300s AD. Then the population began to decline. They lost contact with Norway. By 1500 AD, there were no Norse left in Norway.

What happened?

The climate changed - cooled by 1-2 deg C. The increase in sea ice made trade difficult. The cooler weather damaged hay yields, possibly already declining due to overgrazing. There were conflict with the Inuit, who were better adapted to the colder climate. In other words, climate change helped trigger the complete collapse, to use Jared Diamond's term, of the Norse society in Greenland (note the word "helped": climate is rarely the sole cause of societal collapse).

The lesson from the "Vikings farmed in Greenland" is not just that the climate has varied in the past. That's obvious, that's something for which we have decent data, and again, it does not prove or disprove the human role in current climate change. Once again, the fact the climate can change naturally does not mean that it is the only way the climate can change.

The real lesson of the "Vikings farmed in Greenland", the one that appears in textbooks, that one that appears in history courses, climate courses, archaeology course, you name it, is that a lack of resilience in the face of a changing climate can lead to the breakdown of a society.

Will and the others who repeat the Greenland was meme are not missing the facts. They are missing the point.


Tuesday, March 10, 2009

By boat, by train, by plane, by bike

Good Magazine published this fun comparison of fuel per passenger required to travel 560 km (350 mi) by various modes of transportation, including the fuel used to create the food that fuels the walker and the cyclist.

The winner? The cyclist at 912 miles per gallon, or 0.26 L/100 km.

The cruise ship at the top of the chart gets a rather sad 0.009 mpg. So if cram more than 101,133 passengers on the ship and don't feed any of them, you may be able to can match the efficiency of a bicycle (ignoring how the mass of all those people would reduce the fuel efficiency of the ship).


Saturday, March 07, 2009

The great disruption

Thomas Friedman hits on a point that is not getting nearly enough attention:

What if the crisis of 2008 represents something much more fundamental than a deep recession? What if it’s telling us that the whole growth model we created over the last 50 years is simply unsustainable economically and ecologically and that 2008 was when we hit the wall — when Mother Nature and the market both said: “No more.”

We have created a system for growth that depended on our building more and more stores to sell more and more stuff made in more and more factories in China, powered by more and more coal that would cause more and more climate change but earn China more and more dollars to buy more and more U.S. T-bills so America would have more and more money to build more and more stores and sell more and more stuff that would employ more and more Chinese ...

Is it about time to unite the financial collapse with ecological collapse?

“Just as a few lonely economists warned us we were living beyond our financial means and overdrawing our financial assets, scientists are warning us that we’re living beyond our ecological means and overdrawing our natural assets,” argues Glenn Prickett, senior vice president at Conservation International. But, he cautioned, as environmentalists have pointed out: “Mother Nature doesn’t do bailouts.”

One of those who has been warning me of this for a long time is Paul Gilding, the Australian environmental business expert. He has a name for this moment — when both Mother Nature and Father Greed have hit the wall at once — “The Great Disruption.”...

Often in the middle of something momentous, we can’t see its significance. But for me there is no doubt: 2008 will be the marker — the year when ‘The Great Disruption’ began.


Friday, March 06, 2009

Photo of the week

In the past year, I've heard from a couple colleagues who work in the Caribbean about the large spread of lionfish, a colorful reef fish native to the Indo-Pacific. It is thought that a few lionfish were accidentally introduced through a broken tank at a large private aquarium in Miami and/or by some hobby aquarium owners.

You can find them now in many parts of the Caribbean, apparently including Cuba, where I spotted this fellow under a rock a couple weeks back. I'm definitely not an expert on lionfish, but you don't need to be an icthyologist to spot this aptly named species!

A welcome new addition to Caribbean reefs? Not quite. As if Caribbean coral reef ecosystems were not already under enough pressure, lionfish are invasive predators that are capable of removing much of the native reef fish stock and altering ecosystem dynamics [any experts wish to elaborate in the comments?].

If you are interested, the US Geological Survey has a terrific Google Map showing all the reported sightings across the Caribbean, including the recent sightings in the Florida Keys.


Wednesday, March 04, 2009

Making a list of scientists and checking it twice

The meme about a list of "scientists" who disagree with the IPCC consensus made its way to the Coral List, a list-serv maintained by NOAA and read by by a range researchers, educators, divers and marine park managers. There are a few of these lists floating around out in the ether, the most infamous being the US Senator Inhofe's 650 club. So every once in a while a line about a list of scientists almost as long or longer than the list of IPCC authors appears in an op-ed piece in a newspaper, a post on a reputable web site, or in a discussion on a good service like the Coral-List.

This is my argument (to the Coral-List) about the folly of these lists of, based on an article I wrote for Worldchanging:

The goal of the list-makers is ostensibly to show there are more "scientists" who doubt the IPCC consensus than who participate in the IPCC. This misses the point of the IPCC effort entirely. The IPCC was not created to get the views of ~2000 climate scientists. It was created to have those ~2000 climate scientists summarize the findings of the entire scientific community.

Let’s say you are worried about your health. Maybe you’ve noticed an elevated body temperature, and it is beginning to affect the way you function.

You go to the doctor. The doctor gives you a diagnosis, based on her or his expertise. To be safe, you might get a second opinion. Most of the time, that’s enough. But this diagnosis is a frightening one. And you want to be thorough. So you make a call to the United Nations.

The UN assembles a team of a couple thousand of top doctors from around the world, with a range of specialties. The team of doctors does a comprehensive review of all the scientific literature on your condition and charges medical centers around the world to run sophisticated computer models simulating your health. The information is assembled into a massive technical report. A draft report is then made available for any doctor in the world to review. Thousands of
people review aspects of the report and provide criticism that is factored into the final draft. The team of doctors also then meets with representatives from different countries around the world to produce a summary of the report in less technical language that reflects the
most important and statistically significant findings. Five years later, you are given that summary.

That is how the IPCC reports and the “Summary for Policymakers” reports are produced. They are the end-point of an exhaustive review of scientific literature by a group of top scientists and a long peer review process. They are not alarmist. The findings contained in the reports
actually tend to be quite conservative, because they arise out of a wide body of research and adhere to strict statistical conventions. For example, the projections for sea level rise are lower than in many climate studies because of reported uncertainty in the understanding
of ice sheet dynamics.