Saturday, March 4, 2017

Has Global Sea Level Rise Increased to 5 mm Per Year?

There has not been a great deal of media coverage about the past 3 years of increase in the rate of sea level rise. Global sea levels have risen by an average of about 5 mm (0.2 inches) in each of the past 3 years. This is a significant increase versus in 3.3 mm (0.13 inches) increase per year during the satellite era (1993 to present). As shown below, the rate of sea level rise jumped up above the trend line in late 2014 and continued to rise in 2015. Sea level rise has remained above the trend, with another big jump in the most recently posted result (the period ending November 30, 2016)

Is sea level rise accelerating? There are a couple of valid reasons to question whether the past 3 years signals an increase in the rate of sea level rise. Time will tell whether an increase in the rate of sea level rise began in 2015 or not.
  1. The increase in sea level rise during the last three years may be due to El Nino. The warm global temperature and other weather impacts of El Nino may have produced the increase in the annual sea level rise. Sea level rise may revert back to 3.3 mm per year in non-El Nino years. 
  2. Three years of higher sea levels is probably not a long enough period to confirm a change in the trend of sea level rise. Although the increase in sea level rise during the satellite era is on a fairly linear trend, the annual results are rather noisey. However, if the past three years does indicate that sea level rise is now increasing at a faster pace, the consequences for coastal areas are dramatic. 
Whether or not an acceleration in the rate of sea level rise has begun has enormous implication for the future of coastal areas. Thirty years of 0.13 inches of sea level rise would result in a 4 inch increase. However, thirty years of 0.2 increases would lead to a 6 inch increase. Tidal flooding is already a serious problem. An additional 2 inches of sea level rise (6 instead of 4) would lead to billions of dollars in damage.

And of course, many climate researches are predicting that the rate of sea level rise is going to go parabolic, and that 6 inches of sea level rise in the next 30 years is an unrealistically optimistic scenario. As shown below, the NOAA intermediate prediction (green line) is for about 1 1/2 feet of sea level rise within the next 30 years.

Saturday, November 12, 2016

Does Record Low Antarctic Sea Ice Foreshadow Collapsing Glaciers?

The media and climate science deniers have been remarkably quiet about rapidly disappearing Antarctic sea ice. The sea ice extent in Antarctica is the lowest in satellite record history for
this date in the year. As shown below, Antarctic sea ice extent has fallen below the previous record low extent for November 11, set in 1986. The Antarctic Sea Ice extent of 15.3 million km is 600,000 million km lower that the old 1986 record (yellow trend line). This is a larger area than is covered by Spain. It is also 2.4 million km below the 2013 level for this date (dotted green line)

For a clearer, interactive version of the above graph, follow link and click on the "Antarctic" button 

According to National Snow and Ice Data Center "the rapid early reduction in sea ice cover in this region may create favorable conditions for the break up of the eastern Peninsula ice shelves at the end of austral summer. Similar sea ice trends and weather conditions were present during the spring seasons preceding past ice shelf retreats (e.g., 2001 to 2002)."

Sudden melts can lead to hydrofracturing that can devour an ice shelf nearly the size of Rhode Island in hours or days. While catastrophic sea level rise from the collapse of Antarctic glaciers is probably unlikely to occur for decades, it would not be surprising if there is a spectacular collapse of either an ice shelf or glacier at some point during this year's Antarctic melt season. This year's Antarctic melt season may not lead to a significant rise in sea level, but in future years as Antarctica melts, it's not a question of if Miami will be underwater, but whether or not it will occur before 2100.

Related Articles

Friday, October 9, 2015

Why Hasn't Ted Cruz Been Called Out For Using UAH Data To Deny Global Warming

Ted Cruz is passionate in his denial of global warming. And if you listen to him, he has his message down pat. But an aspect of his denialism that he doesn't seem to get called out on is his use of temperature records from the University of Alabama at Huntsville. Cruz is ignoring NASA, the UK Met Office, the Japan Meteorological Agency, and numerous other highly respected sources to cherry pick as his source of temperature records the data set produced by global warming deniers at the University of Alabama at Huntsville.

According to the Open Mind blog
There are 5 major sources of global temperature data which are most often referred to. Three of them are estimates of surface temperature, from NASA GISS (Goddard Institute for Space Studies), HadCRU (Hadley Centre/Climate Research Unit in the U.K.), and NCDC (National Climate Data Center). The other two are estimates of lower-troposphere temperature, from RSS (Remote Sensing Systems) and UAH (Univ. of Alabama at Huntsville).
And there are numerous institutions that analyze the data and provide measurements of the global temperature using both satellite generated data and land/sea based temperature stations, as detailed in the Why So Many Global Temperature Records

Maybe it's just me, but I have more trust in NASA, NOAA, the UK Met Office, and the Japan Meteorological Agency than I do in a source that is denying global warming based on estimating the lower troposphere temperature from satellite microwave sounder data, as the University of Alabama Huntsville team is doing. In fact, The Journal of Climate published a study that showed why the University of Alabama at Huntsville team was underestimating global warming. Additionally, Skeptical Science posted on why this was a flawed data source.

One of the reasons the UAH data is flawed is due to orbital decay in the paths of satellites. Hmmm, who do you think is better at adjusting satellite data for orbital decay -- a small group of researchers at UAH or the team at NASA? Also, it strains credibility to assume that satellite microwave sounder measurements of the troposphere are a better source of global surface temperature estimates than land and sea based temperature gauges.

Cruz also uses the other source satellite microwave sounder temperature reports, Remote Sensing Systems, to support his global warming denialism. However, Carl Mears the senior scientist at Remote Sensing Systems (RSS) "criticizes Cruz's approach and conclusions". Mears also indicates that it is likely that there are more errors in the RSS reports than in the temperature estimates from  surface measurements.

In addition to Cruz cherry picking his data source, he also cherry picks his time frame. His "zero warming" claim is based on using an abnormally warm outlier year, 1998, as the starting point for his claim that there has been no warming in the past 17 years. There is significant variability in temperature from year to year, and it's hard to take seriously a trend analysis based on cherry picking an outlier year as the staring point. The upward trend in global surface temperatures is obvious to the naked eye if any of the other nine years in the 1990's is utilized as the starting point.

Ted Cruz's climate denailism sort of falls apart once you realize that it is based on his cherry picking a flawed source of temperature records. Legitimate analysis is not based on cherry picking data.

Additional Reading

Rate of Sea Level Rise Has Doubled Since 2014. Trend or Outlier?

Sea Ice - Another Climate Science Denier Claim Melts Away

Sunday, September 20, 2015

Sea Ice Has Declined by 900,000 Square Miles This Year

The sea ice extent at the north and south poles has undergone a massive decline this year. Antarctic and Arctic sea ice extent have declined by 1.83 million and 550,000 square kilometers, respectively, in the past 365 days. Thus, total sea ice extent has declined by 2.4 million square kilometers (over 900,000 square miles). For perspective, this reduction in area covered by sea ice at the poles is 5 and a half times the size of California.

Antarctic sea ice declined from 20.1 million square kilometers to 18.3 million kilometers on September 20 from 2014 to 2015 according to the National Snow & Ice Data Center. Arctic sea ice declined by from 5.1 million kilometers to 4.5 million square kilometers during this period. (For reference, 1 square kilometer equals 0.386 square miles)

Antarctic Sea Ice Extent
(area of ocean with at least 15% sea ice extent

Click on image to view interactive larger version of this chart (next click on Antarctic button)

Arctic sea ice is in a long term downtrend. This year featured the lowest maximum extent and fourth lowest minimum in recorded history. On the other hand, Antarctic sea ice extent had been increasing from 2011 through 2014. The trend in Antarctic sea ice extent abruptly reversed in July, 2015. In the past year Antarctic sea ice has gone from record extent to a below average extent (average based on 1981-2010).

Arctic Sea Ice Extent
(area of ocean with at least 15% sea ice extent

Click on image to view interactive larger version of this chart

It's probably questionable whether combining Antarctic and Arctic sea ice extent generates a particularly meaningful metric. The warming planet is the primary reason for shrinking Arctic ice, whereas there are complicated counter balancing factors at play in the Antarctic,  The changes in extent between the two poles are not equivalent. The numerous factors influencing Antarctic sea ice extent create interactions that are the subject of ongoing research. Some scientists have speculated the melting land based Antarctic glaciers may produce incremental sea ice, while others are focusing on wind patterns.

It is also suspect to focus on data from a single year, as opposed to multi year trends. Despite these qualifiers, the decline this year should put to bed the idiocy spouted by climate science deniers that global warming is a hoax because sea ice is increasing. The deniers' claim that the decline in Arctic sea ice was compensated for by an increase in Antarctic sea ice was always absurd, and at this point can only be made by cherry picking results from periods that exclude July through September 2015.

Additional Reading

Friday, September 4, 2015

Rate of Sea Level Rise Has Doubled Since 2014. Trend or Outlier?

During the past year and a half, the rate of sea level rise has doubled. Sea level has risen at a rate that projects out to over 0.2" per year.  The sea level rise over the last 20 months has jumped from the previous two decades rate of 0.1".  Given that there is a great deal of variability in the rate of in sea level rise on a short term basis, it's hard to judge whether the sea level rise is accelerating, or if this increase is just a short term aberration.  As shown in the chart below, while the trend in sea level is clearly upward, there is a great deal of variability on a year to year basis. During the past two decades, any big jumps or declines in sea level rise have been followed by reversion to the trend line.

If the sea level rise is carried out to an additional decimal point, the sea level has been rising at a rate of 3.2 mm ( 0.12") per year over the past couple of decades. Thus, being more precise, the rate of sea level rise since the start of 2014 has increased from 0.12" to more than 0.24" annually.  (for reference 0.1" is equivalent to 2.54 mm)

For a finer level of detail, monthly reports on sea level rise are provided by CSIRO

The rate of sea level rise has enormous implications for long term planning purposes. If the rate of sea level rise reverts to the mean and continues at 0.1" per year, then it may be decades before rising sea levels cause massive problems. If an annual sea level rise of 0.2" is the new normal, then there is likely to be a dramatic increase in tidal and storm related flooding in less than two decades. And if the rate of sea level rise continues to accelerate, as the vast majority of climate researchers predict, sea level could rise by 8" or more by mid century. 

Sea level rise offers a dramatic example of why proposed actions to reduce greenhouse gas emissions are so controversial. The majority of today's voters may well be dead before the impacts of rising sea level become catastrophic, sometime between 2050 and 2100. Given the uncertain long term benefits of various actions to reduce fossil fuel burning, and the immediate economic pain to be caused, solution aversion is an understandable reaction. Of course, for those that care about the world that they are leaving to their grandchildren and/or hope to still be around in 2050, continuing down the current path of annual global emission of 9 billion metric tons of CO2 is frightening.

With the past year and a half  being the hottest in recorded history, it's not surprising that there has been an increase in the rate of sea level rise. The high recent temperatures are in part due to El Nino. Thus, once El Nino conditions end, there may be a small decrease in global temperatures and sea level rise.  However, on a long term basis, climate researchers predict that the rate of sea level rise will accelerate. As shown in the following chart, the projected rise in sea level becomes a huge problem after 2050. If these projections are correct, the current refugee problem in Europe could become exponentially worse as coastal areas become uninhabitable.

The costs of dealing with rising seas will be enormous. Miami has already spent $15 million on pumps to keep tidal waters from rising on city streets and plans on spending an additional $500 million. Miami's spending may only be a pittance compared to the future cost of defending against coastal flooding. The authors of a study published in Nature Climate Change suggest that spending
of $50 billion per year will be required through 2050 to defend against coastal flooding.


Climate researchers have warned that sea levels rise is accelerating. It's logical to conclude that glacial and arctic ice melt will occur at a more rapid rate in a warming world. Time will tell whether the acceleration in sea level rise started picking up speed in 2014.

Tuesday, August 18, 2015

Has Growth in Antarctic Sea Ice Extent Suddenly Halted?

Antarctic sea ice extent has barely increased so far this month. In a typical year, Antarctic sea ice extent would have increased by over a million square kilometers during the first half of August. There is no telling whether the results of the last few weeks is just an aberration or the start of a trend.

However, the minimal growth of Antarctic sea ice extent makes a mockery of claims being made by climate science deniers as recently as last month. A favorite tactic of climate science deniers is to claim that the growth in Antarctic sea ice extent offsets the decline in Arctic sea ice extent. And while this type of comparison was misleading even when the Antarctic sea ice extent was expanding, it is downright absurd this month in which the Antarctic sea ice extent has returned back to it average extent during 1981-2010.

While Antarctic sea ice extent has been flat lining during a winter period when it usually expands, Arctic sea ice extent has been melting faster during the past few weeks than it did during the most recent couple of years.

It seem ludicrous that Christopher Booker of The Telegraph was claiming "How Arctic ice has made fools of all those poor warmists" back on  July 25, 2015. In his article, Booker made of point of indicating Arctic sea ice extent was higher in 2015 than in 2013 and 2014. Well, as one can see from the image below, Arctic sea ice in 2015 has been both above and below that of the previous two years over the course of this year. However, on the date Booker published his article, Arctic sea ice extent was already trending lower than the previous two years, and has stayed lower throughout August. In fact, based on the current trend, it seems likely that 2015 Arctic sea ice extent summer melt minimum will be the 5th lowest in recorded history, and well below the levels of 2013 and 2014. He also made the spurious argument that Antarctic sea ice growth counterbalanced Arctic sea ice declines. Well, that claim goes up in smoke due the sudden halt in expansion of Antarctic sea ice extent this month.

Time will tell whether the increase in Antarctic sea ice extent has come to a halt. It would not be surprising if there is some increase of the ice extent during September or early October, the period when Antarctic sea ice extent reaches it's annual winter maximum. However, it is not unreasonable to speculate that Antarctic sea ice extent may have returned back to its average range. 

Related Articles

Monday, August 17, 2015

The Revised Republican Presidential Candidate Message on Climate Change - "It's natural"

During mid-January, 2016, it will be announced by NASA, NOAA, and the Japan Meteorological Agency that 2015 was the hottest year in recorded history (Given that 5 of the first 7 months during 2015 have been the hottest for their respective history, it is not so much a question of will 2015 be the hottest year in recorded history, but one of "by how much will it be the warmest?"). At this point, it will become pretty difficult for any political candidate to continue to claim that "global warming is a hoax" without losing credibility among all except those that are in deepest denial. A few Republicans, including Donald Trump, James Inhofe and Rick Santorum, may continue to spout the "hoax" myth, but any candidate that wishes to appeal to a mainstream audience will lose credibility if they deny that we live on a warming planet.

A logical mantra for a presidential candidate that wants to appeal both to the Republican base during the 2016 primaries and also to a mainstream audience during the general election, is to indicate the warming of the planet is "natural". This claim that the warmth of 2015 is "natural" can be supported by indicating that it is part of a trend that has been going on in the short term since the end of "the little ice age" and in the long term since the end of the "ice age".

Given that most of the 2016 Republican primaries will be held during winter, the seasonally cold weather will probably dampen the attention drawn by "global warming" and thus make it easier to down play this issue.

Joining the consensus of climate scientists, and agreeing that mankind is contributing to climate change is going to be challenging for any Republican candidate. The problem is that American voters are unlikely to accept a position of indicating that there is a problem, but not recommending taking any action in regard to the problem. And the various solutions proposed to combat climate change are antithetical to conservative Republicans. New and/or stricter regulations that limit carbon emissions are a non-starter. Supporting a carbon tax would almost certainly be political suicide for a Republican candidate in the primaries. According to a Rasmussen Reports poll, 65% of voters would be opposed to actions that cost them more than $100 a year,
Forty-one percent (41%) say they’re not willing to pay anything more in taxes and utility costs to generate cleaner energy and fight global warming. Another 24% are willing to spend only $100 more per year.

Here are some of the positions Republican presidential candidates can espouse on global warming:

1. It's a hoax
2. I'm not a scientist
3. The data is inconclusive
4. Climate change is natural
5. Mankind is contributing to climate change

Of the above, the first (hoax) would be damaging in the general election. The fifth (anthropogenic climate change) would be a vote killer during the primaries. The second and third claims above come across as awfully lame. Thus, the most logical position for a Republican presidential candidate on climate change is the fourth above, that climate change/global warming is natural. It's instructive that Lindsay Graham, the only Republican candidate that suggests climate change denial will be a problem for the party in 2016, is barely registering in the polls

Additional Information

For reference here are links to a couple of sites that:1) explain why the rise in global temperatures is not simply a continuation of a trend, and 2) another site that makes the case that recent "global warming" is natural