High blood pressure may be more difficult to control in winter, according to research reported to the American Heart Association, at its meeting in Orlando last week.

A five-year study by a team from the United States found Department of Veterans Affairs analyzed data on 443,632 veterans treated for hypertension at 15 VA hospitals in cities throughout the US found that blood pressures during the summer were on average 7.76% lower than during the winter. The researchers found the same pattern emerged from each hospital they studied, regardless of whether it was based in a warm or cold climate, in locations that ranged from Anchorage, Alaska to San Juan, Puerto Rico.

This is an intriguing finding, and there are a load of potential explanations for it:
A more active summer lifestyle may be the key
It is also possible that people might eat more salty foods in winter, and salt is strongly linked to raised blood pressure
There may also be a link with sunlight. Which can trigger a number of metabolic changes

But I also need to sound a note of caution: blood pressure changes all the time throughout the day. Although the study was all done correctly, it is important to realize that many subtle variations in blood pressure could be lurking within the data.

Nonetheless, people should be aware of the possibility that their blood pressure may be harder to control in the winter, and to be more vigilant at this time.

“For everything there is a season, And a time for every matter under heaven: A time to be born, and a time to die; A time to plant, and a time to pluck up what is planted; A time to kill, and a time to heal; A time to break down, and a time to build up; A time to weep, and a time to laugh; A time to mourn, and a time to dance; A time to throw away stones, and a time to gather stones together; A time to embrace, And a time to refrain from embracing; A time to seek, and a time to lose; A time to keep, and a time to throw away; A time to tear, and a time to sew; A time to keep silence, and a time to speak; A time to love, and a time to hate, A time for war, and a time for peace.”
–The Bible, Ecclesiastes, 3:1-8

“Each new season grows from the leftovers from the past. That is the essence of change, and change is the basic law.”
–Hal Borland (American Writer, 1900-1978)

“Live in each season as it passes; breathe the air, drink the drink, taste the fruit, and resign yourself to the influences of each. Let them be your only diet drink and botanical medicines.”
–Henry David Thoreau (American Essayist and Philosopher, 1817-1862)

There are several reasons for being concerned about climate change. One is that global warming may cause significant changes in patterns of disease.

An analysis published last month in Occupational and Environment Medicine found that global warming will cause more deaths in summer because of higher temperatures but these will not be offset by fewer deaths in milder winters

The Harvard researchers analyzed city-specific weather data related to the deaths of more than 6.5 million people in 50 US cities between 1989 and 2000.

They found that during two-day cold snaps there was a 1.59% increase in deaths because of the extreme temperatures. However, during similar periods of extremely hot weather death rates went up by 5.74%. An important point is that deaths did not rise as steeply when temperature fluctuations were less extreme.

Deaths from all causes are known to rise when temperatures go up while heart attacks and cardiac arrests are more likely when it is very cold. It was anticipated that global warming would increase deaths during hot temperatures but that this would be compensated for by fewer deaths in the winter.

The authors conclude:

“Our findings suggest that decreases in cold weather as a result of global warming are unlikely to result in decreases in cold-related mortality in the US. Heat-related mortality, in contrast, may increase, particularly if global warming is associated with increased variance of summer temperature.”

While all 50 US cities showed similar rises in deaths when temperatures plummeted, more deaths were seen during extreme temperature rises in cities with milder summers, less air conditioning and higher population density.

The authors suggest that this is because the use of central heating is widespread, whereas fewer people have air-conditioning in their homes.

They said:

“Central heating, which constitutes an important adaptive mechanism against cold, is almost universal in the US and this may explain why the US population seemed fully acclimatized to cold.

Making air conditioning universally available may reduce heat-related mortality but would, on the other hand, have a perverse effect by enhancing global warming through carbon dioxide emissions from electricity consumption.”

This advice is very sound.

There are two other points. First, it is sudden changes in temperature that cause the problems: we are quite god at acclimatizing to extremes. But if global warming brings with it more instability in the climate then we will likely see much more of a problem.

Second, and something that is often missed by the naysayers about global warming, is that most of us no longer have a luxury enjoyed by our ancestors: When they endured ice ages and periods of warming, they could simply migrate to a more congenial region.

Most of us are stuck where we are, and that’s the big problem when we think about the health consequences of environmental change.

Today is Earth Day. I am sure that everyone living on the planet is eager to keep it a decent place to live, and the recent flurry of gloomy reports has energized people in a way that I have not seen in decades.

Yes, there are plenty of nay sayers who point to the ice core date and say that there’s not a problem, but that band is shrinking as quickly as the Arctic Ice. Information from the Lake Vostok ice core analysis has provided data going back 420,000 years, during which there have been four temperature peaks before the current one, all comparable to today’s temperature levels. The causes for those peaks are poorly understood, but I am more and more persuaded that something profound is going on with the planet’s weather, and we really have only three choices:

1. Prevent, which may be too late
2. Adapt
3. Mitigate

On April sixth, scientists and officials from more than 100 governments met in Brussels and agreed that Climate change is already under way and the Earth faces water shortages and famines in the poorest countries, plus huge floods and species extinctions if no action is taken to slow it down.

There was an unprecedented consensus on the mounting threat
posed by global warming, and the final report was unanimously approved, even by the United
States, China and Saudi Arabia. The officials from these countries had spent four days and
two nights challenging the more dire predictions line by line.

The
report by the Intergovernmental Panel on Climate Change (IPCC) warns that
global warming will hit hardest in the Arctic, sub-Saharan Africa, on
small islands and highly populated river deltas in Asia.

For example it predicts that 600 million more people could suffer from
droughts in Africa and billions will face risks from coastal flooding
by the end of this century.

And if that seems to far away to be of immediate concern, the report also makes a number of remarkably precise near-term predictions. The 21-page
“policymakers summary” of a full report to be published later this year,
charts the impact of temperature rise over the past 30 years and
calculates the implications of the rise of about 3 degrees Celsius by the end of this
century forecast by another IPCC panel in January.

Rajendra
Pachauri, the chairman of the panel, said: “It’s the poorest of the
poor in the world, and this includes poor people even in prosperous
societies, who are going to be the worst hit. This does become a global
responsibility in my view.”

Professor Martin Parry, who was co-chair of the panel’s working group on climate change
impacts, said evidence of changes already taking place that could be
attributable to human influence had been found in 29,000 sets of data.

He said, “For the first time we are not just arm-waving with models.”

Professor
Parry said actions to adapt to climate change, such as sea defences and
new forms of agriculture, should take priority over efforts to reduce
greenhouse gases, which would take years to have any impact. He went on to say,
“In the near term, adaptation is vital. The sooner we get on with that
the better.” Dr Pachauri revealed that the process had been a “complex
exercise”.

Many scientists objected to what they saw as an unprecedented level of
interference from government officials in arriving at what is meant to
be a scientific summary.

Professor Parry added that: “I don’t think it is the right thing to say the message was watered down.” Though he conceded that the scientific team made some compromises in their final report. As an example he revealed that a graph showing that billions would be at risk of coastal flooding by 2080 was changed to read “millions”.

Joseph
Alcamo, who is an American-born professor of environmental science and
engineering at the University of Kassel in Germany, said: “I question why
it needs to be such a difficult fight to get the science out there.
Scientists have to play a role we are not really trained for. It is a
dilemma for us.” Professor Alcamo chaired the working group studying changes
in Europe. He reproted that he had appeared on the podium to confront
skeptical governmental delegations at 2am, after some objected to his use of the term “unprecedented” to describe the heatwave in Europe in 2003 which claimed up to 35,000 lives.

For the first time, the scientists broke down their
predictions into regions, and forecast that climate change will affect
billions of people.

Africa will be hardest hit. By 2020, up to 250 million people are likely to be exposed to water shortages.

According to the report, in some countries, food production could fall by half.

North
America will experience more severe storms with human and economic
loss, and cultural and social disruptions. It can expect more
hurricanes, floods, droughts, heatwaves and wildfires, it said.
Northern Europe will at first experience some benefits, such as a
reduced demand for heating, but southern Europe will face more
heatwaves and drought, with a reduction in crop productivity.

Parts
of Asia are threatened with widespread flooding and avalanches from
melting Himalayan glaciers. Europe also will see its Alpine glaciers
disappear.

These were the Key Points from the report:

• There is clear evidence that from all continents that climate change is happening now
• The key “tipping points” are in the Arctic, small islands, sub-Saharan Africa and Asian “mega-deltas.”
• Coastal flooding threatens “bilions” of people in low-lying delta regions with high population growth
• In Asia, climate change could put close to 50 million people at risk of hunger by 2020, with that number rising to 132 million by 2050 and to 266 million by 2080
• By 2080, between 1.1 billion and 3.2 billion people
  will face water shortages, and between 200 million and 600 million will
  face extreme hunger.
• Up to 30 per cent of animal species face displacement or extinction with average warming of 2 degrees C.
• If temperatures rise more than 3C, sea level rise threatens a third of coastal wetlands.
• Cereal productivity will drop globally with a rise of between 1 degree C and 2 degrees C - which could happen by 2050.
• Some impacts are already unavoidable due to past emissions

There remain some disagreements:

• The United States, China, Russia and Saudi Arabia objected to the
  statement that there is “very high confidence” that climate change is
  impacting on “many natural systems, on all continents and in some
  oceans”.
• The United States objected to the statement that North America could suffer “severe economic damage” from warming.
• The United States
  led objections to the statement that European heatwave of 2003, which
  killed more than 20,000, was “unprecedented” but was routed by
  scientists.
• Billions affected by sea level rise changed in some places to millions.
• One
  illustration full of specific numbers - that up to 600 million more
  people in Africa were having difficulty finding water, and that 5,000
  more heat-related deaths in Australia followed a 2 degree C temperature rise -
  was dropped after skeptical governments, including the United States, objected.

The publication of this report coincided with another published in the journal Current Biology
showing that more than half of the tropical coral reefs in the world are being degraded beyond repair. And 30 million people depend entirely on coral reefs for their income and for their food

This report also address the effects of climate change on disease and the threat that it will provoke wars over scarce resources. Those may be dealt with in more detail later in the year.

You may be interested to look at a projected timeline for some of these likely changes.

Despite these gloomy predictions, there is some cause for optimism: even if some were dragged in kicking and screaming, this is the first time that so many countries have agreed about ANYTHING. And secondly, the imminence of these changes hsould stimulate not just conservation and technological innovation, but a greater understanding that we cannot continue to live as we have done in the past: the planet is a great deal more fragile than our economies.

There a very important piece of research published in this week’s issue of the prestigious New England Journal of Medicine, indicating that air pollution increases the risk of cardiovascular disease, at least in women. The whole article is available for free download.

Researchers from the University of Washington studied 65,893 postmenopausal women without previous cardiovascular disease in 36 U.S. metropolitan areas from 1994 to 1998, with a median follow-up of 6 years. All the participants were aged 50 to 79 and part of the Women’s Health Initiative, a major US Government funded investigation into the causes of heart disease in women. A total of 1,816 women suffered one or more cardiovascular event.

The investigators were particularly interested in tiny airborne particles called particulates, which are less than 2.5 microns across, and can lodge in the lungs. Previous research had incriminated them in heart disease. These are the dense clouds that you see coming out of chimneys or exhaust pipes. They found that pollution levels varied between four to nearly 20 micrograms per cubic meter.

Each 10 microgram rise was matched by a 76% rise in the chances of dying from heart disease or stroke. For women living within, rather than between, cities, the risk more than doubled, increasing by 128%, with each step up in pollution levels.

It is not clear whether women are more susceptible to pollution than men. Women’s coronary arteries are smaller and this might render them more vulnerable.

These results suggest that the risk from air pollution is far greater than most doctors previously thought, though it is still not clear how these sooty particles lead to the development of heart disease.

I live just outside a city where we often have smog advisories for weeks at a time in the summer. This research adds to the growing evidence that air pollution should be taken seriously as a risk factor for cardiovascular disease.

That also means that when localized air pollution is particularly high, people with chronic lung disease or coronary heart disease should avoid staying outside.

This problem will likely get worse as the summers be progressively warmer.

Yet another reason for taking climate change seriously.

“For the first time in the history of the world, every human being is now subjected to contact with dangerous chemicals, from the moment of conception until death.”
–Rachel Carson (American Biologist and Writer, 1907-1964)

As expected the Intergovernmental Panel on Climate Change (IPCC) concludes that there is more than a 90% chance that global warming has a human cause. The panel said that temperatures were probably going to increase by 1.8-4 degrees Celsius (3.2-7.2 degrees Fahrenheit) by the end of the century. It also projected that sea levels were most likely to rise by 28-43cm, and global warming was likely to influence the intensity of tropical storms.

The findings are the first of four IPCC reports to be published this year.

Also as expected, the attacks on the report began even before it was published. Some radio critics have committed a fundamental mistake of saying that people have been warning of this for years and nothing has happened. First, something has happened, and second, the report is careful to say that precise estimates are difficult. It is the direction of change which should be of greatest importance.

The Mail and Guardian Online is reporting that some scientists and economists have been offered $10 000 each by a lobby group funded by one of the world’s largest oil companies - ExxonMobil - to undermine the report.

There is also a very well reasoned article about the semantics of climate change. The precise language of science and the quite different way in which politicians and many marketing people use language. It is well worth reading.

My main concern remains the impact of climate change on health and well-being. And many parts of the world, from Florida to the Horn of Africa are already experiencing that.