Wednesday, 26 August 2015

How Climate Change threatens the world's natural heritage

Not just Palmyra.

In July New Scientist reported that 35 World Heritage sites are threatened by climate change. That's nearly one in six of the sites listed because of their natural value. They include shrinking glaciers in Argentinia's Los Glaciares National Park and the washing away of birds nests by higher sea levels in Germany's Wadden Sea.

In  most cases climate change isn't the only factor. In Los Glaciares alien species, like cows and dogs, and increased visitor numbers create problems. In the Galapagos its much the same whilst in Mexico's Butterfly Biosphere Reserve commercial logging is a factor. Of course, these factors threaten that large majority of sites and habitats that aren't special enough to have World Heritage status but which are still important for the preservation of biodiversity and recreation.

Look behind the headlines and you see the same four causes:
  • More people - who need homes and food.
  • More prosperity - especially in China - which increases the demand for meat, minerals, travel, etc.
  • More development - both to meet local needs and to provide exports to the developed countries.
  • Unnecessary use of fossil fuels - driving climate change.
 Consumer capitalism has lifted billions out of poverty but it now threatens the natural world.

Can renewables meet the need?

A recent tweet celebrated the supposed fact that at peak, recently, Germany derived 25% of its power from solar. The source given was data published by the Fraunhofer ISE at https://www.energy-charts.de/power_de.htm.  But is the claim true?

Actually no. The highest proportion in recent weeks was reached during August 2nd when a combination of low demand, low winds and strong sun produced about 56% of Germany's electric power from solar pv. A very good result - though obviously excluding fuels used for space heating, travel, etc.

But it's a power number - a measurement over a short time - specifically the middle of the day. There is no solar power at night and not much in the early morning and evening. A bit of rough analysis for a more representative day, 27 July in fact, shows that solar produced 22% of the power at peak but 10% of the day's energy. Extra investment in solar PV could increase the peak as much as you like - even to 100% - but that would still need over 50% of the energy to come from somewhere else (possibly wind or a storage system).

And this is mid summer.

A similar analysis for January shows a solar PV power peak of c8% but providing only c2% of the day's electricity. And the average over that week is much worse.

Is wind the answer? Sort of. Germany gets more energy from wind than from solar PV and it's available at night and in winter. But it's even less predictable than solar. At midnight on January 5th it provided just 3% of the needed electrical power.

Moreover periods of low wind can last for days - there was almost no wind for the whole seven days starting January 17th.

There are partial low-carbon solutions - nuclear, tidal, hydro, import of power from very large new solar farms in north Africa and various kinds of storage - but they all have their own problems.
Any responsible plan for our energy future must show how it would cope with periods like 17 to 14 January - and at what cost.

Sunday, 16 August 2015

Halfway to catastrophe!

Two weeks ago New Scientist reported the results of a kind of mini systematic review of global temperatures since 1850. In it Michael Le Page argues that the best baseline period - to give the temperature before global warming started - is 1850 to 1899. For convenience some temperature series use 1880-1899 as their baseline but this is misleading because temperatures in the 1880s were depressed by the eruption of Krakatoa.

When the five available temperature series are adjusted to use 1850-1899 as baseline it's clear that four of the five will show more than one degree of warming before the Paris IPCC conference this Autumn.

That's halfway to the the two degree level generally thought to imply a strong probability of catastrophic climate change.

Le Page continues with the prediction that unless we take "drastic action" the Earth will reach that two degree point by around 2050.

Friday, 24 July 2015

Natural heritage in danger

197 World Heritage Sites were selected because of their natural character. Of these 35 are threatened by climate change - the nearest being the Waddensee in north Germany.

Ironically the only natural character site to lose its world heritage status, the Arabian Oryx Sanctuary, did so because Oman decided to allow oil prospecting!

Thursday, 23 July 2015

Sea level rise - No anomaly

Climate scientists had been concerned by an apparent slowing of sea-level rise over the last decade despite the increasing volume of run-off from glaciers. A recent paper in Nature Climate Change (DOI: 10.1038/nclimate2635) resolves the anomaly.

The authors showed that the rate of sea-level rise for 1993 to 2004 had been overestimated by about 20% due to inadequate calibration of the satellite-mounted altimeters. The new value, 2.6 to 2.9 mm/year, implies an acceleration in the rate of sea-level rise since 2004.

Friday, 7 November 2014

Repeating the fate of Carthage?

Did you know that the Romans sowed the fields of Carthage with salt after defeating it in the second Punic War?

If so, you know a myth!  Apparently this was invented quite recently!

Unfortunately, our salting of fields is all too real. An international research team points out that poor irrigation practice often leads to salt deposition causing production losses. They cite research showing that in India salt-affected fields produce 40 to 60% less than those not affected.  The team estimated the annual costs due to lost crop yields and additional costs at $27 billion per year.

Salt damage can be reversed - but it's not cheap.

Monday, 27 October 2014

Species Loss: It's later than you think

How many species are going extinct?  It's an impossible question, not least because we don't know how many species there are. We do, of course, know pretty accurately the numbers of species of birds, mammals and reptiles. The big uncertainties apply to insects, beetles and plants. 

The low estimates are two million species and of which we are losing 0.01% per year. That implies a loss of 200 species pa. Other estimates are as much as ten times greater implying  a loss rate of 20,000 species per year.

But the real frightener is that even these numbers may be a serious underestimate.

The main driver of species extinction is widely believed to be habitat loss but it has proved difficult to prove this quantitatively. However, work by Stefan Dullinger and Franz Essl (of the University of Vienna) and co-workers appears to have resolved this puzzle. In research published in 2013 (PNAS, April 30, 2013. vol. 110, no. 18) they showed that species loss in many species does not occur when the habitat is destroyed or degraded but decades later.

An analysis of threatened species from seven taxonomic groups and 22 European countries showed that the number of such species was best explained by what had happened in 1900. The most useful variable was the intensity of land use - or how much of the production of the land we humans take for ourselves. This accounted for 35% of threatened species - twice as many as were predicted by land use data for the year 2000.

It's not hard to see why. 

Intensification of land use such as deforestation or even hedgerow removal does not usually kill every member of a species but it does reduce their numbers and creates smaller, more or less isolated, populations. These populations are vulnerable to accidents, in-breeding, human disturbance and further habitat loss. Over a period of decades rare events become rather likely causing the small populations to become extinct. Even where physically possible isolation prevents recolonisation of the area and the species moves towards extinction.

What this means, practically, is that we have seriously under-estimated the impact of the human activity on the natural world because much of it has not yet happened. And, insofar as our predictions of future impacts are based on our experience those impacts are also under-estimated.

A separate study by Oliver Wearn and co-workers at Imperial College (Science, 337, p 228) estimates that deforestation to date will ultimately eliminate 5% of species of Amazonian birds, mammals and amphibians. However, if deforestation continues at its present rate Amazonian species loss will reach 40% by 2050 and may ultimately reach 65%.

And this, please note, is before we assess the impacts of climate change!

Pessimists are surely right to consider ours the time of the Sixth Great (species) Extinction - comparable to the asteroid strike that killed the dinosaurs. 

The difference is that the asteriod did not know what it was doing.  We do.