Wednesday, 26 June 2013

Water in the Desert: A Tale from Mali

The River Niger is a geographical oddity. It starts in the hills of Guinea then runs away from the coast into Mali, finally reaching the ocean thousands of miles later.

Each year seasonal flows flood the wetlands near Mopti in Mali, creating a rich ecosystem that feeds fish, migrating birds, cattle and some 1.5 million people who live there. Not, perhaps, for much longer.

Fred Pearce has reported two threats to this ecosystem. Upriver from the wetlands engineers are diverting water from the river to create, by irrigation, new farmlands; farmlands that the government of Mali has given to foreign companies. In 2012 the proportion of river water averaged 8%, but went as high as 70% during the dry season. According to Lansana Keita, the engineer in charge, the barrage is supposed to release at least 40 cubic meters per secoind at all times but sometimes doesn't: "We do our best, but irrigation has priority."So far the wetland area has been reduced by 600 square kilometers and fish yields have fallen. The government of Mali plans a tenfold expansion in new commercial farmlands. Irrigation for this will require the whole flow of the river during the dry season.

And further upstream, in Guinea, the government plans a new hydroelectric dam. This would capture most of the wet season flow. According to dutch hydrologist Leo Zwarts, who has modelled the effects, the combined effect will be to dry out the wetlands about every four years creating poverty, starvation and driving more than a million people off the land.

There's an obvious precedent for this - the Aral Sea. The sea lost 80% of its volume between 1960 and 1998 due to diversion of water for agriculture. The results for pollution, health and losses of livelihoods and biodiversity that have been horrible and widely reported. We might have hoped that the government of Mali and its foreign partners would have noted the lessons. Yet Jane Madgwick, head of Wetlands International, has described the likely results for Malean wetlands as a “human catastrophe as vicious and shameful as the drainage of the Aral Sea". 

Finally (I think) we should note that the mighty river Niger does not end in Mali. What about the downstream users?

When the River Niger leaves Mali it flows into Niger and then into Nigeria. (You can tell its importance from the country names can't you? It's the largest river in both countries!) What will be the consequences for them? And what might they do to avoid those consequences?

This is a depressing tale with a number of lessons:
  • Intensive commercial farming and irrigation schemes may increase food production in a country. Much of the extra food, and profit, will be exported making the local benefits somewhat uncertain and likely to accrue to the local elites.
  • They may create poverty and hardship for existing farmers, fishers and herders. These people are unlikely to be compensated for their losses.
  • We should therefore be highly skeptical of plans to address Africa's problems by encouraging large-scale commercial farming.
  • These problems are not specific to either capitalist or state socialist systems. They reflect drives for status, profit and production that are found in all economic systems plus the fact that national planners are remote from the people and places most affected and are unconstrained by an effective political system.

Thursday, 20 June 2013

Has the US cut its emissions?

You may have seen reports that US greenhouse gas (GHG) emissions fell 3.8% last year; they were all over the media last week. The fall since 2005 is said to be 12%. The main factor driving the fall is a switch from coal to natural gas due, in turn, to the availability of cheap gas from fracking (shale gas) though the recession has also contributed.

That’s good news – but nothing like as good as it looks.

The emissions numbers count gas burnt but ignore gas lost during extraction and transfer to users (Wall Street Journal (18/4/13, Since natural gas is mainly methane and methane is much worse for the climate than CO2 ( it takes only a little methane leakage to offset that saving in CO2 emissions.

To see how much we have to set a timescale and I choose 20 years because that is the critical period for addressing climate change. If we have not solved it well within that period it will be a lost cause.

Because methane is such a potent greenhouse gas there will only be a saving of greenhouse gas emissions relative to coal if leakage is less than 0.7%. In 2011 Robert Howarth and co-workers at Cornell University estimated the leakage in the US at 3.6% to 7.9%, exclusive of accidents. They conclude that switching from coal to shale gas will increase the greenhouse effect of this fuel use by a factor of 1.2 to 2 over 20 years! The effect over 100 years is roughly zero.

Suppose that half of the apparent fall in greenhouse gas emissions was due to a switch from coal to shale gas (which is plausible).  Then the 12% reduction in CO2 would imply that the reduction in total greenhouse gas emissions has been somewhere between 5% and nothing. 

The switch from coal to shale gas is not a solution to the problem of climate change and has no part to play unless the leakage can be very greatly reduced and the other environmental effects eliminated. 

Nor is that the end of the bad news – unlike the policy-driven reductions we seek the US reduction is price-driven and is therefore not locked in. Specifically:
  • Part of the GHG reduction is due to the recession and will likely be reversed as the recession ends.
  • Natural gas prices have been rising so US users have begun to switch back to coal.
Finally, low gas prices in the US have led the US to export the coal it would otherwise have burnt – mostly to Europe!

Fossil fuels are a global market and local prices falls will only increase fuel usage. We can only reduce GHG emissions if we raise the price of fossil fuel.

Nasty but necessary.