How deforestation and climate change may be related to flash floods during northeast monsoon season 2021-2022

Animated map of northeast monsoon winds and rain on Sunday, 2 January 2022, 9 am to 10 am (Source: Windy app)

Deforestation and urbanisation in Southeast Asia have been contributing to warmer temperatures, resulting in a chain reaction of stronger air turbulence and more extreme weather events such as stronger monsoon winds and heavier storms, leading to more severe floods.

The floods have also been exacerbated by the increase in sediments from the exposed soil eroded by the rain that are washed into rivers, as well as the increase in surface runoff from the heavy rain that fell onto the impermeable ground, which was once covered with trees that were able to intercept and absorb most of the rainwater.

Singapore has been lucky to escape the brunt of the most recent northeast monsoon storms, but who knows, we may be the next target after Selangor and other states were heavily hit on 16-18 December 2021, followed by Johor on 2-4 January 2022.

Monsoon rains causing floods in Selangor and other states in Peninsular Malaysia on 18 December 2021; monsoon winds and rains causing floods in Johor, Malaysia on 2 January 2022; the reddish areas show highest rain intensity (Sources: Government of India & Windy app)

On 21 December 2021, a news article reported:

“Meanwhile, Dr Siew of Cent-GPS said Malaysia should use this incident as motivation to focus on cutting down emissions, stopping deforestation and creating a dialogue with the masses.

“The government must enact a climate change act which will give an integrated approach, from the policy-level to our disaster response. It’s also a way to integrate the role of society and NGOs in organising support for disaster response,” he added.”

It is a very important lesson indeed. This is what Singapore ought to do as well since we are located in the monsoon zone together with Malaysia.

Floods in Kuantan, Malaysia, caused by torrential downpour on 16 December 2021 (Source: Wikipedia)

Urban heat island effect and climate change (A simplified explanation)

Let’s talk about wind for a start. 🌬️

I don’t profess to know all about wind, but maybe I can learn something new while sharing whatever little I know.

Physics teaches us that air flows from a high pressure area to a low pressure area.

That’s how wind is formed.

When a land area is heated up by the sun, parcels of air rise and condense to form clouds in the sky.

The rising air parcels cause the area to become less dense, creating low pressure.

The air from areas of high pressure will flow in as wind.

Air flows from a high pressure area to a low pressure area. (Source:

Some surfaces heat up faster than other surfaces, hence creating different areas of high and low pressures.

At the beach, the land heats up faster than the sea during the day, hence air flows towards the land as sea breeze.

On land itself, concrete buildings and asphalt roads heat up faster than parks and forests.

What happens when more forests are cut down to make way for cities?

We experience the urban heat island effect. 🌆

More heat. Stronger winds. More turbulence.

Urban heat island effect (Source:

Multiply this effect over time and space, and we will get more extreme weather changes, such as more intense and/or prolonged storms, heat waves, droughts, etc in different parts of the world.

In the longer run, we describe the phenomena collectively as “climate change”.

When measured in terms of the average time span of 35 years, climate may be observed as predictable meteorological patterns, which are fairly constant.

Weather is less predictable, as it changes daily, or even hourly.

Of course, in a much longer term, such as thousands or millions of years, climate changes significantly.

That’s how we get ice ages in between long periods of global warming.

But in the Anthropocene that we live in, climate changes faster than ever before, due to unprecedented emissions of carbon from human activities, such as:

🌳 Deforestation to make way for urbanisation
🌳 Burning of fossil fuels for energy, transport, etc

This is where we are.

On a global scale, winds are influenced by the Coriolis effect, which has to do with Earth’s rotation. 🌏

Coriolis effect (a simplified animation) Source:

It causes prevailing winds to rotate clockwise or anti-clockwise, depending on whether they are in the Northern or Southern hemispheres.

That’s how we get monsoons, cyclones, typhoons and hurricanes in different regions of the world, which are being made more extreme by climate change.

These severe weather events may result in natural disasters, such as flash floods, landslides, mudslides, slope failures, etc, which in turn may cause property damage, injuries and/or deaths of people who are affected.

Sumatra squall in Singapore, caused by the southwest monsoon.

Note: This post is meant to provide only a simplified explanation of climate change. Besides wind, temperature and rain, other weather elements, such as humidity and cloud cover, have a part to play in climate too. Local weather cycles affect global weather cycles, and vice versa. To make things more complicated, deep ocean currents also affect the climate on continents.

Deforestation and flash floods: How they are all connected

Deforestation in Bidadari and Lorong Ah Soo may have contributed to the flash floods in the surroundings during an intense storm on 2 November 2020.

It is believed that due to climate change, more extreme weather changes can be expected.

Yesterday, flash floods occurred in several places in Singapore during such a heavy downpour.

Although floods aren’t new occurrences in low-lying countries like Singapore, they may be exacerbated by ongoing deforestation.

According to TODAY’s article dated 2 Nov 2020:

“In photos shared on social media, murky brown water can be seen inundating parts of a road along Hougang Ave 3 near the Singapore Girls’ Home.


In a Facebook post at around 3.15pm, PUB said that flash floods had occurred along Upper Paya Lebar Road, Lorong Gambir near Bartley as well as Mount Vernon Road.”

Murky water flooding Hougang Avenue 3 on 2 Nov 2020 (Photo by SG Road Vigilante Facebook Group)

It is interesting to note that these places are also the locations where deforestation is taking place.

Deforestation is underway in Bidadari (around 90 ha) to build a new housing estate.

Deforestation for housing development in Bidadari (Photo taken on 2 Jan 2020)

Likewise, deforestation is taking place south of Lorong Ah Soo.

Is it any wonder why flash foods are happening all of a sudden during a heavy downpour in the vicinity?

It is a clear sign that we have reached a point we can no longer ignore the negative consequences of destroying our few remaining dense forests in Singapore to our own detriment.

But when concerned citizens and nature lovers decry the ongoing deforestation, they get labelled as “negative” and “complaining”.

Have any of us remembered our Geography lessons in school where we learn that replacing the porous soil of the forest with impermeable concrete and asphalt surfaces will result in greater surface runoff?

How deforestation contributes to flooding (Source:

It isn’t sufficient to simply apply superficial band-aid solutions by building artificial rain gardens and so on.

We need deep ecological solutions to deal with the root cause of the problem of flash floods, increased urban heat island effect and so on.

We need to seriously consider redeveloping brownfield sites such as golf courses and other underutlitised or unused existing built-up lands, instead of sacrificing our few remaining dense forests such as Bukit Batok Hillside Park, Clementi Forest, and so on.

To sign the petition to conserve Bukit Batok Hillside Park, click here.

To sign the petition to conserve Clementi Forest, click here.

Lessons from recent Nepal earthquake – safety precautions

If you are outdoors and an earthquake happens, stay as far away from buildings as possible in case any nearby building collapses.
If you are indoors and an earthquake happens, take cover underneath a sturdy table or equivalent as soon as possible to avoid being hit by any falling objects.

Footage shows the moment the devastating earthquake shatters Nepal More:

Posted by Mashable – Video on Thursday, April 30, 2015