I know what I want

But I just don't know

How to go about getting it

      -Jimi Hendrix

Well I guess
That I just don't know
    -Velvet underground

I really don't know
Clouds at all

     -Joni Mitchell

Greetings

First a couple of weird news stories.

   Here's one where folks from  NOAA  saying sea level rise could be 3 meters by 2050.   That seemed a little soon to me.  Here  it is from the Insurance Journal: 

"Margaret Davidson, NOAA’s senior advisor for coastal inundation and resilience science and services, and Michael Angelina, executive director of the Academy of Risk Management and Insurance, offered their take on climate change data in a conference session titled “Environmental Intelligence: Quantifying the Risks of Climate Change.”

Davidson said recent data that has been collected but has yet to be made official indicates sea levels could rise by roughly 3 meters or 9 feet by 2050-2060, far higher and quicker than current projections. Until now most projections have warned of seal level rise of up to 4 feet by 2100.

These new findings will likely be released in the latest sets of reports on climate change due out in the next few years.

“The latest field data out of West Antarctic is kind of an OMG thing,” she said."

I wonder if the 12 million or so residents whose property will be under water in 30 or so years are aware of this?   

"More than half of the area of 40 large cities (population over 50,000) is less than 10 feet above the high tide line, from Virginia Beach and Miami (the largest affected), down to Hoboken, N.J. (smallest). Twenty-seven of the cities are in Florida, where one-third of all current housing sits below the critical line — including 85 percent in Miami-Dade andBroward counties. Each of these counties is more threatened than any whole state outside of Florida – and each sits on bedrock filled with holes, rendering defense by seawalls or levees almost impossible.

By the metric of most people living on land less than 10 ft above the high tide line, New York City is most threatened in the long run, with a low-lying population count of more than 700,000. Sixteen other cities, including New Orleans, La.; Norfolk, Va.; Stockton, Calif.; Boston, Mass.; St. Petersburg, Fla.; and Jacksonville, Fla.; are on the list of places with more than 100,000 people below the line. (Much of New Orleans is already below sea level, but is protected at today’s level by levees.)

(Here's a handy tool from NOAA to see your favorite city under water.)

      And here's a story about clouds.   It seems that the climate models all assumed that clouds would be reflecting light much more than the data shows.  See Scientific American  Clouds wont save us from Global Warming

"Analysis of the first seven years of data from a NASA cloud-monitoring mission suggests clouds are doing less to slow the warming of the planet than previously thought, and that temperatures may rise faster than expected as greenhouse gas pollution worsens—perhaps 25 percent faster...

Tan, meanwhile, said it would be a mistake to focus too closely on the exact [climate sensitivity] number. The sensitivity result from the modeling experiments should be taken “with a grain of salt,” she said.

That’s because the study was based on a single model. A main point in conducting the experiments was to show that climate models contain a bias that could be corrected. The group hopes other scientists will conduct similar experiments using different models to help hone in on a more reliable measure of climate sensitivity."

OK, so where does that leave us?    -Here's an article from the Washington Post. .   It points out that  although  we are poised to sign the Paris accords, we neither  "know what we want", nor "how to go about getting it"    Here are few problems.

      " 1. Knowing when we cross the threshold. The first problem is simply with knowing when the world is actually 1.5 degrees C or 2 degrees C above a pre-industrial baseline temperature, often taken to be the average between the years 1850 and 1900 (though this, too, is disputed). Indeed, some havenoted that we breached the 1.5 degree threshold in February of 2016, albeit only for the space of a single month (which probably isn’t what scientists have in mind when they think of truly crossing a climate threshold).

The problem is both that it will be hard to define where the actual threshold lies, and also hard to be sure when we’ve crossed it, given differing baselines and periods of analysis, and the fact that temperatures will always fluctuate up and down. And there’s an even bigger problem, which involves so-called “overshoot” scenarios in which the world emits too much and presumably warms up more than 1.5 or 2 degrees Celsius, but then starts to mass-produce “negative emissions” technologies that pull some carbon dioxide back out of the air again.

If this happens, we also will not know, for some time, how long it will actually take to get back to 1.5 or 2 degrees C, moving in the opposite direction, once we’ve overshot. “It may not be known for many decades if 1.5C/2C has been exceeded or successfully avoided,” Peters notes.

2. Knowing how much we can emit. And then there’s the problem of the carbon “budget,” which the U.N.’s Intergovernmental Panel on Climate Change defined as no more than 1,000 billion tons, or gigatons, of carbon dioxide emissions (emitted from the year 2011) if we want a 66 percent chance or better of holding warming to 2 degrees C.

This number, too, is shot through with uncertainty. For instance, Peters notes that if you can tolerate less assurance of reaching 2 C, then you can suddenly allow for the possibility of vastly higher emissions: “The total quota for a 2C threshold increases by 800 GtCo2 for a decrease in the likelihood from 66% to 50%,” he notes. He also adds that there are big uncertainties related to the role of non-carbon dioxide gases, like methane, in shaping these budgets.

3. Knowing the future. Finally, the so-called “integrated assessment models” that are employed to determine if and how we can actually stay under a given temperature threshold often include the assumption of new technologies that don’t exist yet, or new policies that aren’t in place, to help us get there. An example of the former would be massive carbon dioxide removal from the air — and an example of the latter would be setting a global price on carbon emissions.

These technologies and policies could develop in the future — but then, they also might not. “Nearly all the literature informing global climate policy uses these strong policy assumptions,” Peters writes, referring to global carbon taxes included in models. “There is an urgent need for scenarios based on more realistic policy assumptions, in addition to a broader range of technological pathways that capture political realities.”