By Ian Williams, NBC News correspondent
Even where the land has not gone, it is becoming harder and harder to live on. A two-hour drive north of Gabura, we stopped in the village of Kamira Bazar.
Like much of the delta region, it floods each every year, but the flooding has been getting worse, the waters are staying longer, and contaminating the fields and the wells with salt.
I stood looking over the flooded fields that belonged to Sheikh Shetta. "It's never been this bad," she told me.
"We haven't been able to grow anything properly here for five years." Water from the local well is no longer drinkable.
As Rahman, the environmentalist, puts it: "Climate change has a taste, and it tastes of salt. Freshwater is being polluted and contaminated and overcome by saltwater."
This area borders India, where the authorities are building a border barrier, a high fence of reinforced barbed wire that cuts through the paddy fields. Soon it will completely encircle Bangladesh, 2,100 miles of it.
International migration, millions of poor and desperate people pouring across borders, is a sensitive subject here, but it is clearly one factor in India's thinking. The fence is due to be completed by March next year.