On Sunday at noon, many thousands of concerned citizens will be marching to the United Nations in Manhattan to protest the lack of progress to reduce global carbon dioxide emissions, with the 2013 rate at its fastest rate ever.  Each year, believe it or not, 80,000,000,000,000 pounds of carbon dioxide are dumped into the atmosphere by us humans.  I was a panelist on Wednesday at an event at the Church of the Holy Trinity, and laid out reasons to march, beginning with the future impacts on New York City, but concluding by looking more broadly at the moral reasons we need to act to reduce our climate impact.

In 2013, our emissions were about 80,000,000,000,000 pounds of carbon dioxide, or about 22,000,000,000,000 pounds of carbon (10 Gigatons)

There are three main future direct impacts of climate change on NYC:  (1) heat waves will be increasing, making life more difficult in the city — we all know it can get disgusting when it gets over 90 degrees in the summertime, and it is projected that the number of these heat wave days will double or triple by the 2050s. (2) Cases of extreme rainfall have been on the rise already in our region, and will continue to increase.  And (3) sea level rise, which is one of the most guaranteed impacts, though the exact amount to expect is still highly uncertain.  Sea level rise is a very serious problem, especially for low-lying neighborhoods and cities (e.g. Miami).

I’m an oceanographer and will focus more on sea level rise, but am a member of the New York City Panel on Climate Change (NPCC), so I can speak to the science of any of these topics.  After Hurricane Sandy, the NPCC was reconvened by Bloomberg, and here are the main conclusions of relevance to coastal flooding:

• By the “2050s” sea level rise median forecast is about 1.5 feet (the “low end” 10th-percentile projection is 8 inches, and the “high end” 90th-percentile projection is 32 inches)
• Future changes to storms by 2050s for the NYC region are not well known
• For the total number of North Atlantic hurricanes, the direction of change is unknown
• The number of intense hurricanes is “more likely than not” to increase

The media and advocates for climate policy tend to try to focus on the danger of climate NOW so focus on storms, but the science of storms and climate is not settled.  So, I prefer to speak about the sea level rise, as it is more of a guaranteed impact of climate change and will eventually transform our coastlines and coastal cities.

The NPCC projections cover a range of different future decades out to 2100, but I choose the 2050s because it is within most of our lifetimes and the typical planning time for people’s lives, such as a 30-year mortgage on a home.

Sea level rise has not accelerated dramatically (yet).  Global sea level rise rate has roughly doubled comparing the 20th century to the last 20 years.  In New York City, we’re getting 1-2 inches of sea level rise per decade right now — this is NOT dramatic, but it in total, we’ve had a foot of sea level rise in the past century, and it already adds up to regular flooding problems for low-lying areas.

Speaking in more detail about what the median estimate of 2050s sea level rise would mean for our city and for the world, let me illustrate some of the problems.

• Many more low-lying city areas will have “nuisance flooding” from rainfall and regular high tides
• A higher risk of a devastating Sandy-like flood, as the extra sea level raises the flood heights
• Many other areas of the world will experience a dramatic rise in flooding problems and building levees and incurring high expenses to protect property
• Beaches will become less natural, more man-made, or even potentially disappearing and only being walls in areas where there are neighborhoods that need flood protection.  A higher rate of sea level rise means a larger need for dredging sand up from offshore (“replenishment”), and eventually this will be deemed too expensive, starting with poorer countries and lower population beach communities of the United States (e.g. Fire Island, Long Beach Island, Hatteras).

New York City is turning 350 years old this year … looking ahead 350 years or more, what are the long-term implications for NYC and the rest of civilization? (and speaking to the church audience: For that matter, “God’s creation”?)

Scientists have coined a new term: “committed sea level rise“, which is the amount of sea level rise that will still occur from a given year onward even if emissions were immediately halted.  Emissions of carbon dioxide have a long residence time in the atmosphere (centuries), so cause an enhanced greenhouse effect for centuries.  The response of ocean warming and expansion takes a long time to occur.  The melting of ice takes an even longer time to occur — this is because the thicker ice is, the longer it takes to melt, and we are talking about miles-thick ice on Antarctica and Greenland.

All this slowness all together is a form of inertia.  While we’ve been fortunate in our lifetimes that sea level rise reacts slowly, when we stop the emissions, the sea level rise and our impacts we have created will worsen for hundreds and perhaps even thousands of years!

The current estimate of committed sea level rise is about four feet, which would (WILL, actually) play out over many hundreds of years.  Every decade of inaction we add about one more foot to our commitment.  Every decade we have increasing emissions, the sea level rise we impose on future generations accelerates and becomes more unmanageable.  Another new term was created that summarizes this well:  Inter-generational injustice.

Is it really our place to impose these kinds of impacts on future generations and on the planet?

Is it our place to drive accelerating sea level rise so that beaches will be turned into seawalls?

Is it our place to turn coral reefs into dust, due to ocean acidification by our carbon dioxide emissions?

Is it our place to have snowy peaks melting to mud?  New York’s mountains will eventually no longer have regular snowpack in the winter.

Is it our place to leave behind a world where populations in many areas are struggling even to survive because the local climate there is no longer habitable, for example because mountain ice has melted and no longer provides drinking water?

Some damage is already unavoidable.  But by acting sooner and stronger to limit emissions and resulting climate change, we can reduce these impacts.  On Sunday, this is why I will bike across town to the west side of Manhattan, and then march to the U.N. in what is likely to be the largest climate change demonstration ever.