Sea Levels Rising for 500 Years?

Rising sea levels in the coming centuries is perhaps one of the most catastrophic consequences of rising temperatures. Massive economic costs, social consequences and forced migrations could result from global warming. But how frightening of times are we facing? Researchers from the Niels Bohr Institute are part of a team that has calculated the long-term outlook for rising sea levels in relation to the emission of greenhouse gases and pollution of the atmosphere using climate models.

The results have been published in the scientific journal Global and Planetary Change.

"Based on the current situation we have projected changes in sea level 500 years into the future. We are not looking at what is happening with the climate, but are focusing exclusively on sea levels," explains Aslak Grinsted, a researcher at the Centre for Ice and Climate, the Niels Bohr Institute at the University of Copenhagen.

Model based on actual measurements

He has developed a model in collaboration with researchers from England and China that is based on what happens with the emission of greenhouse gases and aerosols and the pollution of the atmosphere. Their model has been adjusted backwards to the actual measurements and was then used to predict the outlook for rising sea levels.

The research group has made calculations for four scenarios: a pessimistic one, an optimistic one, and two more realistic ones.

In the pessimistic scenario, emissions continue to increase. This will mean that sea levels will rise 1.1 meters by the year 2100 and will have risen 5.5 meters by the year 2500.

Even in the most optimistic scenario, which requires extremely dramatic climate change goals, major technological advances and strong international cooperation to stop emitting greenhouse gases and polluting the atmosphere, the sea would continue to rise. By the year 2100 it will have risen by 60 cm and by the year 2500 the rise in sea level will be 1.8 meters.

For the two more realistic scenarios, calculated based on the emissions and pollution stabilizing, the results show that there will be a sea level rise of about 75 cm by the year 2100 and that by the year 2500 the sea will have risen by 2 meters.

Rising sea levels for centuries

"In the 20th century sea has risen by an average of 2mm per year, but it is accelerating and over the last decades the rise in sea level has gone approximately 70% faster. Even if we stabilize the concentrations in the atmosphere and stop emitting greenhouse gases into the atmosphere, we can see that the rise in sea level will continue to accelerate for several centuries because of the sea and ice caps long reaction time. So it would be 2-400 years before we returned to the 20th century level of a 2 mm rise per year," says Aslak Grinsted.

He points out that even though long-term calculations are subject to uncertainties, the sea will continue to rise in the coming centuries and it will most likely rise by 75 cm by the year 2100 and by the year 2500 the sea will have risen by 2 meters.

 by "environment clean generations"

Deadline 2014 To Stop Global Warming

Coal-Fired Power Plants Coal-fired power plants, such as this one in the Conesville, Ohio, are by far the 'dirtiest' means of producing electricity in terms of amount of carbon released into the atmosphere. This has made coal a primary target in the effort to keep total emissions of carbon dioxide below the threshold that will yield two degrees celcius of warming. Scientists have settled identified this threshold as the marker for avoiding "catastrophic" consequences from climate change. 

It’s no secret that the world is warming, but a new report published by the World Wildlife Fund suggests we may not have as much time to mull solutions as we think. If the world doesn’t commit to green technologies by 2014, the report says, runaway global warming and economic meltdown are all but unstoppable.

Written by a group at the experts at Australian insurance consultancy Climate Risk, the transformation to a low-carbon world requires an effort “greater than any other industrial transformation witnessed in our history.” At minimum, the world needs to embrace – and by embrace, they mean to the absolute maximum – low-carbon technologies by 2014.

A minimum growth in all green industries of 22% a year is necessary to achieve that goal, according to their research, and that’s just to cut emissions to 63% of 1990 levels by 2020.

But the WWF has more ambitious plans: a reduction to 80% of 1990 levels by 2050, an industrial revolution that would require growths between 24% and 29% every year. This is the best way to stave off the doomsday scenario of 2 degree Celsius (about 3.6 degrees Fahrenheit) warming across the board, according to the report. Unfortunately, we have a long way to go.

The research relied on complex Monte Carlo models of industrial growth, resource allocation, and technological advance, but the basic reasoning is thus: total greenhouse gasses in the atmosphere are estimated 463 parts per million. Scientific research shows that a good comfortable spot for our atmosphere is about 400 ppm. But at around 475 ppm, a threshold that we are dangerously close to crossing, runaway climate change becomes increasingly more likely, at which point it will be difficult if not impossible to put the brakes on global warming.

Now, having said all that, it’s important to note that this isn’t the first doomsday climate change scenario to emerge, especially recently. Just today, two British Cabinet ministers showed off their own doomsday map, detailing rising sea levels and submerged cities that would result from a 4 degree Celsius (7.2 degree Fahrenheit) rise in global temps.

President Obama has pledged a greenhouse gas reduction of 80 percent by 2050 (an easy promise to make with a two term limit), while the EU has stated that it will match those efforts if a deal is sealed at December’s UN climate change conference in Copenhagen.

But the WWF report, if taken seriously, places a new urgency on the issue. For one, most climate strategies rely upon an incremental ratcheting down of emissions while slowly transitioning to low-carbon sources of energy all the way up to 2050.

According to WWF, this schedule simply won’t hack it. Further, WWF points out that only three of the 20 green technologies they’ve reviewed are moving forward fast enough to hit the 2014 deadline: wind, solar, and biodiesel. Other technological initiatives like low-carbon agriculture, sustainable forestry, and other forms of green energy generation are sorely lacking. The outlook, it seems, is dim.

What happens if we miss the deadline? According to the WWF report, from there things become increasingly difficult. Post-2014, low-carbon industries will need to grow at a minimum of 29% per year, and that’s just to have a better than 50% chance of staving off that nearly 4-degree Fahrenheit spike in global temperatures.

But the news isn’t all bad: while the transition will be tough, long term investment in green energies should pay off, with renewable energy savings alone in the period between 2013 and 2050 expected to hit $47 trillion if we cut by 80 percent, a positive number among many grim figures.

Naturally, models are models and scenarios are but scenarios. The most important takeaway is this: no matter whether you believe in runaway warming or not, technology is the way forward in our warming world, and right now we are woefully under-prepared for the transition to a low-carbon future.

by "environment clean generations"