Climate change is making your pollen allergy worse

Spring is time for the glorious beginning of new things. Most people celebrate it, but not the many millions who are hit with sneezing fits and itchy eyes. And things are going to get worse—not just for those who suffer from a pollen allergy, but also for those who never had allergies before.

Read more on Quartz, published May 14, 2015.

Image by mait under CC-BY-NC-SA.

Concerns over geoengineering

The latest studies on solar geoengineering to tackle climate change are reinforcing the case for a global governance system and further study before deployment, as they show that the approach may have little effect on preventing rainfall changes in the tropics — and may even lead to widespread drought in Africa.

Several geoengineering initiatives plan to tackle climate change by cutting incoming sunlight, through methods such as spreading reflective aerosols in the stratosphere. But without also removing carbon dioxide from the atmosphere, such plans would fail to fully mitigate change in rainfall in the tropics, a study published in Nature Geoscience suggests.

Concerns grow over effects of geoengineering,  SciDev.Net, 2 May 2013.

Oceanic carbon sinks: That sinking feeling

Nature has her own way of dealing with excess carbon dioxide. When human activities spew CO2 into the atmosphere, plants absorb more of it than usual, leading to profuse growth. The ocean, too, swallows more than it otherwise would. Many scientists fret that these so-called carbon sinks risk getting clogged up. Some even suggest that this has already started happening.

Ashley Ballantyne, a geologist at the University of Colorado, and colleagues are less gloomy. In a paper published recently in Nature they show that over the past 50 years Earth’s absorption of CO2 has nearly doubled. Yet they see no evidence of a slowdown in the rate at which this takes place. If the climate models suggest otherwise, the researchers argue, then the modellers must have got their sums wrong.

One reason, points out Jean-Baptiste Salée, an oceanographer with the British Antarctic Survey, might be that little is known about how exactly the CO2 is absorbed by the ocean, which quaffs more than half of the man-made stuff. There has been much speculation about this, but little hard evidence. Theory points to three main mechanisms: mixing the ocean’s surface layers (up to a few hundred metres) by wind; mixing of deeper layers by ocean currents; and eddies, swirls created when warm ocean currents meet cold ones, blending large swathes of the ocean 10-100km across. It had been assumed that most of the CO2 is captured by the surface layers, which would then be stirred by wind, distributing the carbon dioxide over a larger patch, and pulled down by ocean currents, freeing the surface layers to absorb yet more.

To test this hypothesis Dr Salée’s team examined a decade’s worth of data from thousands of robots and hundreds of ships spread across the southern hemisphere ocean, approximately between the southernmost tips of Africa, Australia and South America, and Antarctica, whose large, unbroken waters take in most of the world’s man-made CO2. Every nine days the robots dive to 2km and then slowly come up to the surface, recording the temperature, saltiness and speed of currents they encounter along the way. The robots are too small to carry the instruments needed to measure the quantity of dissolved carbon dioxide so this had to be done by researchers aboard ships.

As Dr Salée and colleagues report in in Nature Geoscience, eddies suck up as much carbon as the other two mechanisms do, something most current climate models fail to account for. Dr Salée is quick to urge that the fact that Earth’s carbon sinks seem to be running smoothly for now does not justify complacency. Just as the oceans gulp CO2, they might release vast quantities of it back into the atmosphere. More data delivered by global programmes like Argo, which operates the robot flotilla, and Climate Variability and Predictability, which runs the ships, will help researchers understand how this might occur—and make more accurate predictions about when it is likely to happen.

Also published on


  1. Ballantyne et al.Nature, 2012, 488, 70
  2. Salée et al.Nature Geoscience, 2012, ASAP
  3. Climate change: What lies beneath – The Economist
  4. Argo project, UK Met Office
  5. Climate Variability and Predictability (CLIVAR)

Image from here.

Squirrels and climate change

Winter is a pain in the animal kingdom. Birds can flee it by migrating to warmer climes but grounded beasts, including mammals, have no choice but to stick around. To cope, many species have learned to hibernate. Some, like the Columbian ground squirrel, spend up to nine months of each year in their alcoves. This conserves energy but leaves them with only three months to plump up for the next winter and, crucially, to procreate.

To make matters worse, climate change is leading them to emerge from hibernation later than usual. On the face of it, global warming should mean that the critters have longer ice-free periods in which to go about their evolutionary tasks. But it can also disturb weather patterns, which may have the opposite effect. Jeffrey Lane, an evolutionary biologist at the University of Edinburgh, in Britain, points out that in the squirrels’ natural habitat of the Canadian Rockies, climate change manifests itself in late-spring snow storms.

Because female Columbian ground squirrels remain in their place of birth, the researchers were able to tag and observe them and their offspring each year for the past two decades. A typical female would bear three kittens. On average, only 30% of them survive the first winter, enough to sustain population numbers since female squirrels can expect three or four litters in their lifetime. If the proportion falls, however, the population dwindles.

As Dr Lane and his colleagues report in Nature, in the first decade of the study the number of squirrels dropped just once. But it fell in four of the past ten years. Dr Lane speculates that this might be explained by the fact that over the past 20 years the late snow has delayed the melting of ice by half a day each year, on average, shortening the squirrels’ breeding and feeding season by several days and disrupting their life cycles. Since mothers have less time to squirrel away (if you will) nutrients in their bodies before it is time to hibernate, the suckling kittens are left more vulnerable.

Correlation is not causation, of course, and other factors might be behind the decline in the number of squirrels. But longer winters are unlikely to help.

Also published on


  1. Lane et al.Nature, 2012.
  2. Lane et al.J. Evol. Biol., 2011, 1949.

 Image credit: Jeffrey Lane.

What difference do I make?

The poorest half of the world produces 7% of global carbon emissions. The richest 7% produces half the carbon emissions. – The Economist

An article in the Economist that argued that attempts at curbing population growth isn’t an answer to scarce resources caught my attention because of the two sentences above.

Even without looking at the figures that have been quoted to define the ‘poorest half’ or the ‘richest 7%’, I can safely assume, given that I am a poor graduate student in the UK, that I fall under neither of two categories of the world population. What does that say about my carbon emissions? Not much.

But I know that working in a synthetic chemistry lab that is air-conditioned, living in a house that has central heating and flying back home to India once a year probably means that my carbon emissions lie on the higher end of the spectrum. I do not take pride in this, but the choices that I made with the best intentions for my career have put me in this situation. I am well aware of my situation and I try my best to do something about it:

  • I chose to become a pescetarian.
  • I campaigned for a meatless day a week.
  • I don’t shy away from asking difficult questions.
  • I ensure lights are off when they are not needed.
  • I turn off taps if the water isn’t being used.
  • I turn off the heater in my room when I’m not there.
  • I use a bicycle to go anywhere <10 miles.

I do this despite all the wasteful habits that people around me have. I have housemates who have no qualms leaving lights turned on. I have lab-mates who never think twice before mixing chlorinated waste with non-chlorinated waste. I have friends who won’t mind having a hot water bath everyday. I watch students in college halls everyday pile up food in their plates and then throw heaps of it in the bins because they’re ‘so full’. Every time I watch this happening, a little bunny dies inside me.

If I start calculating how much emissions I cut by following the things I listed above, the number will probably be small. Small enough to make me wonder, especially looking at those around me, what difference do I make?

But then I think that I do what I do not just for the absolute contribution that I make to cut emissions, but also because I care about the environment. I believe that it is important to be as morally responsible to your future generations as possible. I know that beliefs that I build today are going to affect my decisions to tomorrow. These decisions may well have large consequences then.

I’ve had a discussion about these little things that I do with many people. Some of them have wondered whether the effort I put in to doing them is worth the impact they make. Of course I believe the effort is worth it, especially if you take into account the effect of one’s belief systems. But actually, the effort put into doing them is much smaller than most people imagine it to be. Most of the little things I do have become a habit. I don’t have to consciously think that I should turn off the lights or turn off the heater, I just do it.

The other argument that I’ve come across is this: the fact that I do little things I give myself the pleasure of believing that I make some difference. In effect, I am more liable to not worry about the larger problem because in my own little world I am doing plenty. Actually, this argument has got the logic all wrong. If I do the little things, I am only more likely to do bigger things (like giving up meat or campaigning). As I said before, doing these little things has become a habit for me and I don’t derive ‘pleasure believing that I make some difference’ every time I turn off the light in an unoccupied room. So it’s definitely not offsetting me from the larger goal.

What difference do I make? May be very little today but over a life time plenty.