Current Emissions Could Already Warm World to Dangerous Levels: Study

(Photo credit: Wikipedia)

by Andrew Glikson, Australian National University, The Conversation: https://theconversation.com/current-emissions-could-already-warm-world-to-dangerous-levels-study-66040

Current greenhouse gas concentrations could warm the world 3-7℃ (and on average 5℃) over coming millennia. That’s the finding of a paper published in Nature today.

The research, by Carolyn Snyder, reconstructed temperatures over the past 2 million years. By investigating the link between carbon dioxide and temperature in the past, Snyder made new projections for the future.

The Paris climate agreement seeks to limit warming to a “safe” level of well below 2℃ and aim for 1.5℃ by 2100. The new research shows that even if we stop emissions now, we’ll likely surpass this threshold in the long term, with major consequences for the planet.

What is climate sensitivity?

How much the planet will warm depends on how temperature responds to greenhouse gas concentrations. This is known as “climate sensitivity”, which is defined as the warming that would eventually result (over centuries to thousands of years) from a doubling of CO₂ concentrations in the atmosphere.

The measure of climate sensitivity used by the Intergovernmental Panel on Climate Change (IPCC) estimates that a doubling of CO₂ will lead to 1.5-4.5℃ warming. A doubling of CO₂ levels from before the Industrial Revolution (280 parts per million) to 560ppm would likely surpass the stability threshold for the Antarctic ice sheet.

As the world warms, it triggers changes in other systems, which in turn cause the world to warm further. These are known as “amplifying feedbacks”. Some are fast, such as changes in water vapour, clouds, aerosols and sea ice.

Others are slower. Melting of the large ice sheets, changes in the distribution of forests, plants and ecosystems, and methane release from soils, tundra or ocean sediments may begin to come into play on time scales of centuries or less.

Other research has shown that during the mid-Pliocene epoch (about 4.5 million years ago) atmospheric CO₂ levels of about 365-415ppm were associated with temperatures about 3-4 °C warmer than before the Industrial Revolution. This suggests that the climate is more sensitive than we thought.

This is concerning because since the 18th century CO₂ levels have risen from around 280ppm to 402ppm in April this year. The levels are currently rising at around 3ppm each year, a rate unprecedented in 55 million years. This could lead to extreme warming over the coming millennia.

Temperature histories from paleoclimate data (green line) compared to the history based on modern instruments (blue line) suggest that global temperature is warmer now than it has been in the past 1,000 years, and possibly longer. NASA, Author provided

More sensitive than we thought

The new paper recalculates this sensitivity again - and unfortunately the results aren’t in our favour. The study suggests that stabilisation of today’s CO₂ levels would still result in 3-7℃ warming, whereas doubling of CO₂ will lead to 7-13℃ warming over millennia.

The research uses proxy measurements for temperature (such as oxygen isotopes and magnesium-calcium ratios from plankton) and for CO₂ levels, calculated for every 1,000 years back to 2 million years ago.

Some other major findings include:

The Earth cooled gradually to about 1.2 million years ago, followed by an increase in the size of ice sheets around 0.9 million years ago, and then followed by around 100,000-year-long glacial cycles.

Over the last 800,000 years, and particularly during glacial cycles, atmospheric greenhouse gas concentrations and global temperature were closely linked.

The study shows that for every 1℃ of global average warming, Antarctica warms by 1.6℃.

So what does all this mean for the future?

Global warming past and future, triggered initially by either changes in solar radiation or by greenhouse gas emissions, is driven mainly by amplifying feedbacks such as warming oceans, melting ice, drying vegetation in parts of the continents, fires and methane release.

Current CO₂ levels of around 400ppm, combined with methane (rising toward 1,900 parts per billion) and nitric oxide (around 310ppb), are already driving such feedbacks.

According to the new paper, such greenhouse gas levels are committing the Earth to extreme rises of temperature over thousands of years, with consequences consistent with the large mass extinctions.

The IPCC suggests warming will increase steadily as greenhouse gases increase. But the past shows there will likely be abrupt shifts, local reversals and tipping points.

Abrupt freezing events, known as “stadials”, follow peak temperatures in the historical record. These are thought to be related to the Mid-Atlantic Ocean Current. We’re already seeing marked cooling of ocean regions south of Greenland, which may herald collapse of the North Atlantic Current.

A global temperature map for 2015 showing the cold water region in the North Atlantic Ocean. NASA, Author provided

As yet we don’t know the details of how different parts of the Earth will respond to increasing greenhouse gases through both long-term warming and short-term regional or local reversals (stadials).

Unless humanity develops methods for drawing down atmospheric CO₂ on a scale required to cool the Earth to below 1.5°C above pre-industrial temperature, at the current rate of CO₂ increase of 3ppm per year we are entering dangerous uncharted climate territory.

Andrew Glikson, Earth and paleo-climate scientist, Australian National University.

This article was originally published on The Conversation. Read the original article.

10 Years After Katrina, Louisiana Is Becoming A Model For Climate Resilience

by Kate Sheppard Enterprise editor/Senior reporter, The Huffington Post: http://www.huffingtonpost.com.au/entry/10-years-after-katrina-louisiana-is-becoming-a-model-for-climate-resilience_us_55d53afee4b07addcb4586aa

Floodwall/floodgate, New Orleans (G Herbert/Assoc Press)

A decade after Hurricane Katrina devastated coastal Louisiana, forcing 1.5 million residents to evacuate and causing $100 billion in damage, the region is becoming a model for climate change adaptation planning - even if some people in the state still don't want to say the "c" word.

Louisiana's governor, long-shot Republican presidential candidate Bobby Jindal, has been non-committal on climate change. He'll acknowledge it's happening, but says he's uncertain how much humans are to blame.

Nevertheless, Louisiana officials have been planning for rising temperatures and the cascading impacts climate change will have on the state, from rising seas to potentially more dangerous storms. "We are leaders in climate change adaptation, we just don't call it that," said Doug Meffert, executive director of Audubon Louisiana.

The Louisiana coast, with an average elevation of just three feet above sea level and a buffer of rapidly disappearing wetlands, is among the world's most vulnerable regions to climate change. But the state and the city of New Orleans have taken actions in the last 10 years to help make sure recovery from one disastrous storm leads to preparation for challenges the coast will face in the future.

The Louisiana Audubon and a coalition of other environmental groups recently released a report looking at what's been done to make the region more sustainable, from rebuilding failed levees to developing a statewide plan for the coast, and where there still need to be investments.

Overhauling the levees

The failure of the levee system in and around New Orleans has been largely attributed to bad design and inadequate construction, which allowed water to flood 80 percent of the city in the aftermath of the storm. Improving the levees was a top priority, and New Orleans today boasts what has been called the "best flood control system of any coastal community." Congress authorized more than $14 billion for rebuilding the levees and other flood protections after Katrina, leading to the construction of a 133-mile feat of civil engineering.

Those investments have now protected the city against a 100-year flood - a term used to describe a flood whose severity has only a 1 percent chance of happening in any one year. Building to that level of protection has been celebrated as a major post-Katrina accomplishment. But some point out that the system was supposed to be built to at least those specifications before the storm. After Katrina - a 150-year storm for New Orleans and a 400-year storm for other parts of the Gulf Coast - many say the protections should be even stronger.

"Most folks feel like a major city like New Orleans, a major urban center with economic resources, probably should have 400- or 500- standard of protection," said John Lopez, a scientist and the coastal sustainability program director of the Lake Pontchartrain Basin Foundation. Still, Lopez said, the levee system has "definitely improved since before Katrina."

Creation of a central coastal authority

Before the storm, coastal protection from storms and restoration efforts were handled by separate agencies, with some work falling under the Department of Transportation and other work to the Department of Natural Resources. The state legislature moved in December 2005 to unify coastal issues under the new Louisiana Coastal Protection and Restoration Authority, or CPRA.

CPRA is required to submit a plan for ecosystem restoration and hurricane protection to the state legislature each year. The plan is supposed to include CPRA's projects, as well as federal, parish and private restoration work. 

Development of a coastal master plan

The most important part of that unified response under CPRA has been the creation of a state coastal master plan. The plan, to be updated every five years, is meant to outline the state's approach to "achieving a sustainable coast through the integration of coastal protection and restoration projects and programs based on the best science and engineering available."

The first master plan was finished in 2007. Meffert described it "as a learning model." But the most recent master plan, released in 2012, is a "masterpiece," Meffert said, based on sound science for what the region can expect as the climate changes and seas rise. "It did what no other master plan or general plan had done before - drew a map of Louisiana with projects that were impactful and doable, and it really for the first time put on the map what we could save," he said.

The plan includes restoration, structural improvements, and "nonstructural" measures - actions that acknowledge some flooding is likely to happen and that other steps, like raising houses above the flood plain and creating evacuation plans, are also necessary. The 2012 plan includes 109 projects along the coast, and would require $50 billion in investments over 50 years. The state is currently at work on its 2017 master plan. 

Restoring wetlands

A major part of the master plan involves protecting and restoring coastal wetlands, which provide a natural barrier to storms. "We need levees to protect urban centers, but we need our wetlands to protect our levees," said Lopez.

Louisiana has 3 million acres of wetlands, but it's losing them at an astonishing rate - a football field-size area every hour, according to a 2011 U.S. Geological Survey study. The coast is besieged by subsiding land and rising sea levels due to climate change. According to some projections, the Louisiana coast is seeing the highest rate of relative sea level rise in the world.

The outlook for the wetlands is bleak. But hope has come in an unlikely place: the massive settlement resulting from the 2010 BP disaster, which spilled more than 3 million barrels of oil into the Gulf of Mexico. Last month, the Department of Justice announced an $18.7 billion settlement with BP for damages resulting from the spill. Up to $8.7 billion of that could go to Louisiana's coastal restoration efforts. That gives the state a major investment toward the restoration work in the 2012 master plan.

The state, "appears to be putting every cent they can get from BP into funding those restoration protections," said Cynthia Sarthou, executive director of the Gulf Restoration Network. "Sadly, the way we found some of that money was BP." While the BP settlement is "a big step," said Lopez, it's not enough money fund all the elements of the state's master plan. 

A home on the Web

The state has created a public website showing coastal risks and protection projects, launched earlier this year. Housed on Coastal.La.gov, the website for the CPRA, it includes interactive mapping that allows residents to pull up their own address and see both the flood projections and the efforts to reduce risks. The site is helping improve awareness about coastal vulnerabilities, as well as solutions.

"It gives people more of a reality check," said Simone Maloz, executive director of the group Restore or Retreat. "Unfortunately in Louisiana, that's important." 

Beyond restoration and fortification

While the state's various projects are helping make the coastal region more resilient, there is growing recognition they won't always be enough. "Restoration is not always an option, and neither is protection," said Maloz.

This work includes raising individual houses out of the flood plain and educating the public about storm safety and response - work that often falls to parish governments. Maloz said results have been mixed. One bright spot she points to is Terrebonne Parish, which has won funding through Federal Emergency Management Agency grants and state programs to raise more than 1,000 homes. That parish has a waiting list of people who want to elevate their houses.

"They have been able to cobble together all kinds of resources," said Maloz. But the challenge, she said, is that "One parish might be getting it done, doing it right, and neighboring parish might not be even close." To really protect residents of the coast, more attention should be given to these measures, said Sarthou.

"Restoration may take 10 to 20 years," she said. "Storms can happen any year. There needs to be more of an attempt to help those parishes prepare or mitigate damage or flood losses in those communities as we await the results of coastal restoration." 

A man with a plan

New Orleans has a new point person for handling some of those human challenges: Jeff Hebert. He was appointed chief resilience officer in November. Hebert, who also serves as the executive director of the New Orleans Redevelopment Authority, comes from a background in neighborhood revitalization. "A lot of work has been done over 10 years, but much has been done in isolation from one another," said Hebert.

Hebert's resilience officer position was created through a program of the Rockefeller Foundation called 100 Resilient Cities, which aims to unify resilience work within cities and unite municipalities around the world to solve problems collaboratively.

Hebert said he sees his job as addressing three challenges: First, preparing for climate change, which includes homes, businesses and infrastructure, like water management systems. Second, working to connect city residents with job opportunities, particularly in climate-preparation work like coastal restoration and green infrastructure. Third, working to make it possible for people to stay in New Orleans, including financial literacy, access to health care and affordable housing.

Climate change is a large part of that work, Hebert said. "Resilience" requires a better understanding of what climate change, sea level rise and changing storm patterns will mean for the city, and beginning to prepare for that. "We're starting to understand that the future is going to look very different for us," he said.

Hebert's office plans to release a new strategy on Aug. 25 that will lay out a vision for the city. "We've been recovering for 10 years," said Hebert. "Today is the time to pivot from recovery to building the future city."

While many are using the 10-year anniversary of Katrina to reflect on what has been done, it's also an important point for reflecting on what still needs to happen. "We can't confuse recovery with sustainability," said Lopez. "Recovery gives you the opportunity to be more sustainable, but recovery is not sustainable in and of itself. It gives you the opportunity to take the next step."