On pace for 4

[Asrokhel]

Over the years at the U.N. climate talks, the goal has been to keep future global warming below 2?C. But as those talks have faltered, emissions have kept rising, and that 2?C goal is now looking increasingly out of reach. Lately, the conversation has shifted toward how to deal with 3?C of warming. Or 4?C. Or potentially more.

And that topic has made a lot of people awfully nervous. Case in point: The World Bank just commissioned an analysis (pdf) by scientists at the Potsdam Institute looking at the consequences of a 4?C rise in global temperatures above pre-industrial levels by 2100. And the report appears to have unnerved many bank officials. ?The latest predictions on climate change should shock us into action,? wrote World Bank President Jim Yong Kim in an op-ed after the report was released Monday.

So what exactly has got the World Bank so worried? Partly it?s the prospect that a 4?C world could prove difficult ? perhaps impossible ? for many poorer countries to adapt to. Let?s take a closer look at the report:

1) The world is currently on pace for around 3?C to 4?C of global warming by the end of the century. In recent years, a number of nations have promised to cut their carbon emissions. The United States and Europe are even on pace to meet their goals. But those modest efforts can only do so much, especially as emissions in China and India keep rising. Even if all current pledges get carried out, the report notes, ?the world [is] on a trajectory for a global mean warming of well over 3?C.? And current climate models still suggest a 20 percent chance of 4?C warming in this emissions scenario.

2) The direct consequences of a 4?C rise in global temperatures could be stark. Four degrees may not sound like much. But, the report points out, the world was only about 4?C to 7?C cooler, on average, during the last ice age, when large parts of Europe and the United States was covered by glaciers. Warming the planet up in the opposite direction could bring similarly drastic changes, such as three feet or more of sea-level rise by 2100, more severe heat waves, and regional extinction of coral reef ecosystems.

3) Climate change would likely hit poorer countries hardest. The World Bank focuses on poverty reduction, so its climate report spends most of its time looking at how developing countries could struggle in a warmer world. For instance, a growing number of studies suggest that agricultural production could take a big hit under 3?C or 4?C of warming. Countries like Bangladesh, Egypt, Vietnam, and parts of Africa would also see large tracts of farmland made unusable by rising seas. ?It seems clear,? the report concludes, ?that climate change in a 4?C world could seriously undermine poverty alleviation in many regions.?

4) Yet the effects of 4?C warming haven?t been fully assessed ? they could, potentially, be more drastic than expected. Perhaps the most notable bit of the World Bank report is its discussion of the limits of current climate forecasts. Many models, it notes, make predictions in a fairly linear fashion, expecting the impacts of 4?C of warming to be roughly twice as severe as those from 2?C of warming. But this could prove to be wrong. Different effects could combine together in unexpected ways:

For example, nonlinear temperature effects on crops are likely to be extremely relevant as the world warms to 2?C and above. However, most of our current crop models do not yet fully account for this effect, or for the potential increased ranges of variability (for example, extreme temperatures, new invading pests and diseases, abrupt shifts in critical climate factors that have large impacts on yields and/or quality of grains).

What?s more, the report points out that there are large gaps in our understanding of what 4?C of warming might bring: ?For instance,? it notes, ?there has not been a study published in the scientific literature on the full ecological, human, and economic consequences of a collapse of coral reef ecosystems.?

5) Some countries might not be able to adapt to a 4?C world. At the moment, the World Bank helps many poorer countries build the necessary infrastructure to adapt to a warmer world. That includes dams and seawalls, crop research, freshwater management, and so forth. But, as a recent internal review found, most of these World Bank efforts are focused on relatively small increases in temperature.

This new World Bank report is less sure how to prepare for a 4?C world. ?[G]iven that uncertainty remains about the full nature and scale of impacts, there is also no certainty that adaptation to a 4?C world is possible.? That?s why, the report concludes, ?The projected 4?C warming simply must not be allowed to occur ? the heat must be turned down. Only early, cooperative, international actions can make that happen.?

So what sorts of actions might that entail? The International Energy Agency recently offered its own set of ideas for curbing greenhouse-gas emissions and keeping future warming below 2?C. That included everything from boosting renewable energy to redesigning the world?s transportation system. But so far, nations have only made small progress on most of these steps.

Further reading:

? The full World Bank report is here.

? The International Energy Agency recently found that the world is lagging on its climate goals, apart from a recent boom in solar and wind power. But there are plenty of constructive suggestions in the report.

http://www.washingto...k-is-terrified/

[Mulrian]

They seem to think that if everyone meets their CO2 targets then the temperature increases will never happen. It's going to happen like it or not. It's just a matter of how well we can prepare for it and how much we can slow it down.

[Shadrack]

Global Warming is one of those issues where people have based their opinions on emotion and not facts. The vast (very vast) majority of people are not even qualified to give an opinion about Global Warning; prepare for an influx of opinion based on ignorance that is about to hit this thread.

[Andre S. Veteran]

Between extinction of most ocean life due to acidification and overfishing, a dramatic rise of temperature, and quick depletion of natural resources, life on earth is going to be much more difficult in a few decades. This era of ever-increasing economic production and resource abundance has peaked and will soon be history.

This is all due to short-term, egoistical planning, but perhaps that is an innate trait in humans that will lead to our demise. We're programmed to care about our own short, insignificant individual lives rather than the good of the species as a whole; this has worked well up until a certain level of technological advancement, but is proving counter-productive today. Unfortunately we're not about to reprogram ourselves to adapt to this new reality and evolution will not act in time, if it ever could.

Meanwhile, half of the United States still thinks greenhouse gas emissions are no big deal and drive F-150s to go to work every day.

[Growled Member]

I agree. If we don't change our life styles rapidly, the world as we know it will be rapidly changing in the next few years.I hope everyone likes hot weather.