ලක් ජනගහනයෙන් බාගයක්ම 1985ට පසු උපන් අයයි. මෙය වැදගත් ඇයි?

ජනගහනයක මධ්‍යස්ථ වයස (Median Age) කියන්නේ එම පිරිස වයස අනුව එක සමාන කාණ්ඩ දෙකකට බෙදිය හැකි වයසයි. එනම් ජනයාගෙන් හරි අඩක් එම වයසට වඩා බාල වන විට ඉතිරි අඩ එම වයසට වඩා වැඩිමහල්. මධ්‍යස්ථ වයස් අගය කාලයත් සමග ටිකෙන් ටික වෙනස් වනවා.

The median divides the age distribution into two equal parts: one-half of the cases falling below the median age and one-half above the median.

2012දී අවසන් ජන සංගණනය කළ අවස්ථාවේ මෙරට මධ්‍යස්ථ වයස 31ක් වූවා. 2016 වන විට එය අවුරුදු 32.5 දක්වා ඉහළ ගිහින්. ජනගහනයක ළමා හා තරුණ ප්‍රතිශතය කෙමෙන් අඩු වන විට මධ්‍යස්ථ අගය වැඩි වනවා. (60ට වැඩි ජනගහනය ඉහළ ජපානයේ මේ අගය අවුරුඩු 46.9යි. ඉන්දියාවේ මධ්‍යස්ථ වයස අවුරුදු 27.6ක් වන අතර පාකිස්ථානයේ එය 23.4යි.)

අපේ ජනගහනය සම්බන්ධයෙන් බලන විට අද ලක් ජනයාගෙන් බාගයක්ම 1985 හෝ ඊට පසුව උපන් අයයි. ඒ කියන්නේ 1983 කළු ජූලියට පසුවයි. 1987-89 භීෂන සමය ගැනවත් මේ කිසිවකුට හරිහැටි මතකයන් තිබිය නොහැකියි.

1977 ආර්ථිකය විවෘත කිරීමට පෙර තිබූ සමාජවාදී විකාරයන් හෝ 1982 ජනමත විචාරණය හෝ අත්විඳ ඇත්තේ රටේ බාගයකට වඩා අඩු පිරිසක්. රටේ බහුතරයක් දෙනාට මහවැලිය හැරවීම, ඉන්දු- ලංකා ගිවිසුම ආදිය පොතපතින් කියවන සිදුවීම් පමණයි.

මෙය ප්‍රායෝගිකව වැදගත් වන්නේ මේ නිසයි: මෑත ඉතිහාසය ගැන නොයෙක් දෙනා මාධ්‍යවල හා දේශපාලන වේදිකාවල නොයෙක් විග්‍රහයන් කරනනවා. අමූලික බොරු මෙන්ම සත්‍යය විකෘති කිරීම් එමටයි.

මතක තබා ගත යුත්තේ 1990ට පමණ පෙර සිදු වූ කිසිවක් ගැන සෘජු මතකයන් හෝ අත්දැකීම් අද ලක් සමාජයෙන් බාගයකට නොමැති බවයි.

More data: http://worldpopulationreview.com/countries/median-age-by-country/

 

The Day of 7 Billion Humans is here…and we keep counting!

Now playing on a planet dear to you: 7 Billion People...and counting

When I was born in the mid 1960s, the world’s combined human population was around three and a half billion (having passed the 3 billion mark in 1960). In my life time of 45 years, this number has doubled.

We can never pinpoint it exactly, but the world’s demographers have agreed to count 31 October 2011 as the Day of Seven Billion. Sometime today, our human numbers will add up to 7 billion…and keep rising.

That’s 7,000,000,000 living and breathing people — all of who will need to be fed, clothed, sheltered and cared for in many other ways. And they will have higher aspirations in the 21st Century than ever before in history.

If I was too young to remember the day of 4 billion, which was sometime in 1974, I can well remember the last two billion marks.

In 1987 — the year I entered journalism — human numbers passed five billion. A dozen years later, in 1999, the six billion was reached. By then, I too had added my contribution of one co-produced human being (and stopped there).

Of course, it’s not just a numbers game. It’s far more complex, nuanced and dynamic than simply counting people. And as Einstein so wisely remarked, “Everything that can be counted does not necessarily count; everything that counts cannot necessarily be counted.”

During this year, National Geographic magazine is publishing a 7-part series examining specific challenges and solutions to the issues we face. The magazine introduces the series with its January cover story “7 Billion,” offering a broad overview of demographic trends that got us to today and will impact us all tomorrow. The first in-depth story will appear in the March issue, focusing on humans’ impact on the planet’s geology. Other stories will follow throughout 2011.

As I first highlighted in January blog post, this video accompanies the in-depth coverage:

Correction added by NatGeo editors: in 2050, 70% of the population will be living in “urban areas,” not “megacities” as stated in an earlier version of this video.

The Face of 7 Billion is another interactive feature on NGS website. Zoom in on this graphic in which the world’s 7 billion population is depicted by 7,000 human figures, each representing a million people.

A world party of 7 Billion?
In another short video on National Geographic website, Nigel Holmes imagines how much space we would need to host a world party for 7 billion people in 2011.

I don’t like the word population: it sounds cold, clinical and detached. Zoologists can talk about ant populations or elephant populations, but when demographers (and others, including journalists) refer to our the counting of species as human population, I somehow feel it’s too impersonal. Aren’t we more than mere numbers? So in my own writing and TV scripts, I use the phrase ‘human numbers’.

Can you visualise 7 billion?

Semantics apart, our rising numbers are indeed a cause for concern. We didn’t quite see the ‘population bomb’ go off the way we were warned about – thank the secular Force – but we still face formidable challenges.

Our planet’s natural systems are over-stretched not only by our sheer numbers, but also by our technologies and consumption. The many signs of planetary stress include accelerated loss of species, fast spreading deserts, and declining air and water quality. To cap it all, scientists now confirm that human activity is changing our climate.

On the New York Times Dot Earth blog, science writer Andrew C. Revkin regularly examines efforts to balance human affairs with the planet’s limits.