In my opinion:

- Food/Water crises

- Aviailability of Energy

- Environmental pollution

• infectious diseases
• food insecurity
• economic insecurity

1. Poverty

2.Wars

3. Environmental Pollution

I think that the stability of the country is beginning to solve the other problems, because the instability means there is no security and peace in the country. And when peace and security is loosed, there would be difficulties in achieving any progress in the solution of other problems.

I vote for water scarcity, poverty, and injustisce

1. Pollution/ environmental changes

2. Security/ wars

3. Food and water insecurity

Dear  Qasim Mohammed Hussein,

1. Wars and destruction of innocent people  and children in the world.

2. İn some countries the problem of drinking water.

3. The air pollution.

Regards, Shafagat

Three most important problems, needs immediate attention are:

1. Poverty --- majority of countries facing

2. Environmental degradation --- whole world is facing

3. Terrorism --- No country left unaffected

Dear Dr Qasim Mohammed Hussein,

Following may three most crucial problems faced by world:

1.  political instability at global level (most driving variable)

2. Fulfillment of basic needs- Food, Clothing, House/Shelter for all (dependent  variable)

3. Education (one of linkage variables)

Best Regards.

In my opinion, the three major problems facing the world's humans are:

1) Inequality among countries & within countries.

2) Absence of ethical ruling powers. (I mean systems & not individuals)

3) Abundance of political ignorance among the peoples.

Other problems are relatively easier to deal with but these three are behind most of the catastrophes in the world.

Poverty, lack of shelter and lack of education the most affecting factors of people in all over the world.

food

water

health

Poverty 

Food insecurity

Environmental pollution

illiterate population,

curruption 

poverty

Dear @Qasim, these problems are poverty, climate changes, water, biodiversity, ecology and many more. I can not distinct the first three.

Dear @Kusum has mentione the issue of corruption. Good point.

Let me bring you some threads that have good answers, related to your thread.

https://www.researchgate.net/post/What_is_the_most_serious_problem_of_the_todays_world

https://www.researchgate.net/post/Can_science_provide_solutions_for_the_main_problems_of_the_world

https://www.researchgate.net/post/What_in_your_opinion_are_the_gravest_threats_to_contemporary_world_civilization2

Very serious problems are:

1. Drug abuse --- Peer pressure, family issues or an urge to experience a different feeling or thrill and similar things could add up as a reason for a development of this bad habit.

2. Population growth --- The increasing population is destroying nature in order to fulfill their desires which have lead in other natural disaster too, affecting even more on living beings.

3. Poverty --- Poverty has whelmed not just third world countries but also the country like United States. Poverty doesn’t exist by itself, but by the uneven distribution of wealth among the people in t he world.

See link for Top 10 Problems in the World Today.

http://www.factofun.com/top-10-problems-world-today/

I might sound a little cynical, but I think the biggest problem with people is their heads, i.e., ideology, religion, etc. If one day people of the world can really understand and respect each other, then no problem would be a problem. 

Here I list the 10 Biggest Problems In The World According To The EU:

#10 Don't Know

#9 Proliferation Of Nuclear Weapons

Tied #7 Armed Conflict

Tied #7 Spread Of Infectious Disease

#6 The Increasing Global Population

#5 Availability Of Energy

# 4 International Terrorism

#3 The Economic Situation

#2 Climate Change

AND #1 Poverty, Hunger And Lack Of Drinking Water

SOURCE: Eurobarometer

http://ec.europa.eu/public_opinion/archives/eb_special_379_360_en.htm#369

This is another survey by USA Today: 10 greatest threats facing the world in 2014

READ THE FULL REPORT:  http://www3.weforum.org/docs/WEF_GlobalRisks_Report_2014.pdf

http://www.usatoday.com/story/news/world/2014/01/16/wef-biggest-risks-facing-world-2014/4505691/

curruption 

poverty

Environmental pollution

Social problems

Housing problems

Pollution

Low cost

In my opinion:

- Food/Water crises

- Aviailability of Energy

- Environmental pollution

The triumph of social Darwinism (natural selection, struggle for existence, aggressive individualism, elitism vs. ethnic cooperation,mutual help, "moral universe") causes wars, poverty, inequality, injustice, corruption, ecological problems... To M.L.King,"The arc of the moral universe is long, but it tends towards justice"

Let us go further in this thread. Did you know: More than 95 per cent of world’s population faces health problems!

http://www.nbcnews.com/id/44990504/ns/us_news-life/t/seven-big-problems-billion-people/#.VXwx8Pmqp48

http://www.freepressjournal.in/more-than-95-per-cent-of-worlds-population-faces-health-problems/

I see the most problems are be far  from religion and beliefs, climate changes and insecurity

Dear Qasim,

I believe that are:

1. Water

2. Food

3. Wars

Regards,

Vanessa

Dear Dr Hussein,

it’s a philosophical question. It seems, the unbelievers will choose something from the Maslow's hierarchy of needs (e.g. atmosphere, water, food). The believers will find answers from the lists of the human sins, that are popular in their confessional communities. For example, the Orthodox Christians will cite «The Ladder of Divine Ascent» by John Climacus (http://www.prudencetrue.com/images/TheLadderofDivineAscent.pdf). In his hierarchy of sins the supreme human sin (or the reason of all human problems) is a pride, that has no temporal and other limits. So the moral problems will be on the first positions.

With regards,

O.L

Dear Dr. Hussein:

i) Energy

ii) Education

iii) Government and governance

Best regards

Marcos Nobre

Illiteracy, ignorance, and poverty.

energy,   climate change,     curruption 

pollution

diseases (from pollution)

uv killing plants, burning skin

Dear all,

These are excellent answers and the skill and expertise for each of you is highly evident.

The Important Problems of this World Today

http://www.iawwai.com/ProblemsOfThisWorld.htm

Tank you Dr. Subhash for the link, very good chapter

War now  is the most problems facing the Arab  world's population

1. Geopolitics

2. Nuclear threats

3. Terrorism

Recent three main problems:

1. Countries' boarder tensions

2. Internal disturbances

3. Terrorists threats 

Illegal Immigration is taking place due to problems as:

1. Internal insecurity

2. Livelihood problem

3. Shelter seeking

Migration is at the top of the problems nowadays. I do speak about refugee crisis! It may become a catastrophic disaster. 

The European Migrant Crisis Is A Nightmare. The Climate Crisis Will Make It Worse.

http://www.huffingtonpost.com/entry/migrant-crisis-climate-change_55e9ed2de4b03784e275d514

We cannot solve our problems with the same thinking we used when we created them.

 -- Albert Einstein

Problems are not stop signs, they are guidelines.

-- Robert H. Schuller

The main problems are connected with the increasing of the quality of life,good prophylactics,diagnostics and curing.IB Watson for Oncology.http://www.ibm.com/smarterplanet/us/en/ibmwatson/watson-oncology.html

Problems give us opportunities to make life better; subject to effective governance!

Early human diet?

https://www.researchgate.net/post/What_did_early_humans_eat

racism, authoritarianism, lack of enlightened conscience which all cause war.

http://www.iawwai.com/ProblemsOfThisWorld.htm

Overpopulation, poverty, ignorance, and diseases.

Food security, climate change and biodiversity depletion.

Climate change is arguably the biggest challenge we’ve ever faced. Huge expense is needed to prevent and respond to it. This means tempting opportunities for corruption. Some estimates put total investments to offset the effects of climate change at almost US $700 billion by 2020. Most of this will flow through new, uncoordinated channels. There are grey zones and loopholes in regulations, and these risk being exploited by corrupt interests. They’re made more dangerous by pressure to ‘fast-track’ solutions...

https://www.transparency.org/topic/detail/climate_change

Certainly the world population is facing a multitude of problems. Among the most critical and seriously threatening to its development are: climate change and the need to seek new sustainable energy sources, the scarcity of natural resources including water, and terrorism.

My dear colleagues, do sign this initiative.

I have recently signed the Scientists WarningTo Humanity climate emergency initiative. If you are a scientist you can support this new initiative by sharing this and adding your signature here: https://scientistswarning.forestry.oregonstate.edu/

1-Pollution

2-Population

3-Patriotism